Looking for CNC Mill Part I

[planeflier]

Gary,

Looks good!! What software are you using to create your signs?

Keep up the good work.

Planeflier

[OzDragonFlyer]

For clean plunge cutting MDF try a sharp 2 flute upcut -router- bit. Single flutes work ok on edges. Endmills cut ok but the flute geometry needs to be open (although I've used standard 2FL ballnoses for profiling mdf with a lot of success)

Keep in mind mdf is very abrasive and keeps the feedrates as high as your machine can handle, or the tools will quickly lose their edge.

[planeflier]

What is everyone using to cut balsa? I have tried a small bits for cutting printed circuit boards and dremel router bits, but both leave a fuzz around the balsa? Any suggestions?

[balsaman]

I have cut lot's of MDF. I have used regular carbide 2 flute endmills.

[balsaman]

more

[Gary Blaylock]

Thanks everyone!

Planeflier
I am using Autocad for all my drawings. On the motorcycle/pub sign, I tracesd over a bmp. picture I got off the net. I had read where Balsaman did this. On the no smoking sign, I drew it in Autocad in different layers. For the text, I had to trace over Autocad text in order to save as a dxf file. It's a lot of work to do text and I wish I could find an easier way. The hunting club sign was layed out using DeskEngrave for the outside engravings. The inside raise "R" was drawn in Autocad. All work is save (exported as a dxf r12 file). To convert to g-code I have been using SheetCam. I don't think it has been mentioned here but it works really well. I like it a lot better than Ace. SheetCam will show all your cuts, it does the pocketing for the raised lettering
and also contour cutting which will cut on your drawn lines or will cut offset either inside or outside of the lines. It does each layer with the type of cut you assign.

OzDragonFlyer
Thanks, I'll try a two flute carbide router bit. I used a 1/2 in high speed steel bit but didn't get good results. It burned the bit up after about 5 min of cutting. I made the adapter for the end mills hoping they would cut cleaner. They cut about the same but didn't burn. They were four flute center cut. I am using a speed control on my router so maybe by going to a two flute carbide router bit and reduced speed I won't have as many cuts per minute. Am I thinking right?

Balsaman
I have seen lots of your pics. When I first started reading this thread I saw where you were cutting out the clocks. I would like to build one for show. I have downloaded plans off the net. How did you go about getting them into a cad drawing? They really look great and you have done a great job. All of those cut gears would really show off what these routers are capable of.

Any help on a vaccum system?

How about posting pics of things this group has cut on their routers. That should get the jucies flowing!

Gary

[ger21]

Gary, try this for text. http://www.freefirestudio.com/outline.htm

I couldn't get the AutoCAD embedded part to work, but just export the txt as .dxf and load into AutoCAD. A great quick text program.

Gerry

[balsaman]

The clock drawings are available in dxf from the author. You need to email him and ask

[OzDragonFlyer]

If your 4FL was burning up try running the 2FL at the same rpm/feedrate. There's quite a few charts around suggesting feedrates for MDF however I've found that the density of this wood varies so much that such charts are useful only as a guide.

Check the edges of the cut, if there are mill/chatter marks either decrease feed or increase rpm. Obviously if the machine isnt rigid enough it will be hard to get rid of these. On the opposite side, if you are creating a lot of dust or burning the edges, then the cutter is dwelling in the cuts and cutting the chip more than once, creating heat and dulling the tool (making things worse)

Obviously carbide is more expensive but a good investment in mdf cutting (due to mdfs abrasive nature). A little more care is needed and the depth of cut will probably need to be reduced to minimise the risk of snapping the tool. I rarely cut deeper than the tool diameter and have never broken a carbide bit this way. HSS is more forgiving, but won't last near as long as carbide in this sort of use.

Keep trying, practice makes perfect!

[Thermal Miester]

Hi group,

Cranky John has hopefully walked to the PO by now to mail me my plans.

Oz Dragon Flyer or anybody else, why is MDF abrasive?. As a carpenter I have cut my share of the stuff and it has never struck me as particurally blade dulling. It cuts really easy, sands really easy, blah blah blah. I have never cut x # feet of MDF and compared it to how dull the bade get for the same # feet of other material which would be the test I suppose :) .

Complicating matters, not all carbide is created equal. It is a powder compressed and heated and bonded to cutting tools. Wear safety glasses!

I have a Forrest Woodworker 2 tablesaw blade with C4 carbide tips. After cutting over 600 lineal feet of rainforest hardwood, no appreciable dulling!

So anyway, I hope to be working out the electronics and software before the end of the year.

AB

[balsaman]

For those interested,

Here is the clock plans website: http://www.woodenclocks.co.uk/

The above clock was my own design. I like the above plans better.

Eric

[balsaman]

I cut all those gears (3/8 thick) in one pass with a 1/8" carbide endmill. 15" per minute if I remember right. No snappage but probably a faster feed and a couple passes would make the endmill last longer. Mine would get a little dull after a dozen or so gears.

Eric

[CraigF]

Sorry, this has probably all been spelled out, and I'm still reading through the thread and looking at plans... But these steppers are in equipment being scrapped NOW. I set them aside, don't know any more details about them yet, except that they are clean and "work". Is the voltage kinda high for the popular driver boards, so that I'd be using them at the boards' limits? Thanks!

[OzDragonFlyer]

I am guessing they call mdf an abrasive material because the chips aren't cleanly formed like other woods.. being a compressed material there's always a certain amount of particulate matter when a chip is formed, which ends up rubbing against the tools edge like sandpaper. Same thing goes for fibreglass pcb (FRP).

Generally, all the cutting edges of a sawblade are being used when cutting, whereas only partial edges are used on router bits or endmills (especially plunge bits). A typical sawblade would also have more usable cutting surface area than an everyday router bit. So they won't go dull nearly as quickly (with any luck!)

I've had good TCT sawblades which have lasted years of mdf cutting without losing their edge.. And cheap TCT blades which have only lasted a few months. As TM stated, not all blades are created equal :)

[balsaman]

Sorry, this has probably all been spelled out, and I'm still reading through the thread and looking at plans... But these steppers are in equipment being scrapped NOW. I set them aside, don't know any more details about them yet, except that they are clean and "work". Is the voltage kinda high for the popular driver boards, so that I'd be using them at the boards' limits? Thanks!

Will they work? Yes. Will they work well? Probably not. Look for low voltage steppers in the 5 volt range 1-1.5 amps. Your 24 volt steppers will be slow. Maybe they will be good for learning if you want to approach it that way, but it's easier to learn on 5 volt motors so you can use a cheap 12 volt computer supply to run them.

Eric

[ger21]

I am guessing they call mdf an abrasive material because the chips aren't cleanly formed like other woods.. being a compressed material there's always a certain amount of particulate matter when a chip is formed, which ends up rubbing against the tools edge like sandpaper. Same thing goes for fibreglass pcb (FRP).

Generally, all the cutting edges of a sawblade are being used when cutting, whereas only partial edges are used on router bits or endmills (especially plunge bits). A typical sawblade would also have more usable cutting surface area than an everyday router bit. So they won't go dull nearly as quickly (with any luck!)

I've had good TCT sawblades which have lasted years of mdf cutting without losing their edge.. And cheap TCT blades which have only lasted a few months. As TM stated, not all blades are created equal :)


With carbide router bits, the primary cause of dull bits is heat. Commercial CNC routers can cut at well over 1000 ipm, using 1/2" spiral router bits and probably a little less than 20,000 rpm. Most people here use a similar rpm, but cut at less than 50 ipm. This creates a tremendous amount of heat. The best way to make bits last is to cut as fast as possible, with the lowest possible rpm.

If you fed boards through your table saw at 25ipm, your blades wouldn't last nearly as long. :)

Gerry

[CraigF]

Thanks balsaman! Though I do happen to have lots of 24V power supplies, they, and the 24V Japan Stepper Co. motors, are quite unnecessarily large for our purposes IMO. I work in an industrial environment and 24V and 48V is "standard" here for much control stuff. I wonder though if the motors might be worth salvaging for a future mill, maybe for larger stuff where you might need some more oomph?? Anyway, I have to find out their step resolution, may not be much use...but they do look nice and solid!


Re MDF: for me it's a drill bit killer. I happen to drill a lot of 3/4" holes in 3/4" MDF, an $8 3/4" spade bit lasts for only 24 good holes, and 30 holes if I get too lazy to put in a new bit. I'd sure like to find a real good bit for this, but the more expensive ones I've used don't last much longer...I'm sure somebody makes a superbit, I just don't know who.

[balsaman]

One word: "CARBIDE". I am not sure if they make carbide spade bits tho.

[Gary Blaylock]

Hi ger21,
I have OutlineArt and it works like you said but it will only do text in a straight line. I'm looking for some way to do it in arcs and circles simular to the way DeskEngrave does. I believe I read somewhere that CorelDraw will do this and save as a dxf. Have you had any experence with this software?

Hi balsaman,
I had down loaded a plan (DXF) a few month ago from him and look at it in Autocad. I really didn't know a lot about dxf files or in using Autocad at the time. I just remember the drawings with deminsion lines and such on the plans. I knew that with all of the other info on the drawings that I would not be able to use them like they were. I need to get the file back out now and have another look to see if it is drawn in different layers and if I need to explode the drawings and seperate the parts into seperate files. Am I on the right track? I showed the pics of your work to a lot of the people I work with and they could not believe it.

Hi OzDragonFlyer,
I am going to by some two flute carbide router bits this weekend and make some test cuts at different router rpms, cutting speeds, and depths. I have drawn some squares about 4x4 in. to cut in MDF. Maybe after a dozen or two cuts I'll narrow the combination down. MDF cuts, drills, routes, and sand good using hand tools. This is probably do to the fact that I'm a lot faster than my cnc router. The faster my router will cut is 17-1/4 imp. I using 1/2x13 all thread for lead screws but will soon up grade to real lead screws and hopefully maybe double my speed.

I need to lenghten my wire going from my controller to the steppers in order to make a neater installation. What would be the best wire and connectors to use?

I brought my steppers and controller from Dave at HobbyCNC and I'm real pleased with the equipment. My controller has the resistors and I read where the new controller does not. Has any one upgraded from the resistor equipped controller to his new one? Is there any increase in performance or does it just do away with the resistor heat?

Gary

[Gary Blaylock]

Oh I almost forgot,

Cranky,
Could I join the "One Percent Club"?

Thanks again for all the help,
Gary

[HobbyCNC]

Hi ger21,
I have OutlineArt and it works like you said but it will only do text in a straight line. I'm looking for some way to do it in arcs and circles simular to the way DeskEngrave does. I believe I read somewhere that CorelDraw will do this and save as a dxf. Have you had any experence with this software?

Hi balsaman,
I had down loaded a plan (DXF) a few month ago from him and look at it in Autocad. I really didn't know a lot about dxf files or in using Autocad at the time. I just remember the drawings with deminsion lines and such on the plans. I knew that with all of the other info on the drawings that I would not be able to use them like they were. I need to get the file back out now and have another look to see if it is drawn in different layers and if I need to explode the drawings and seperate the parts into seperate files. Am I on the right track? I showed the pics of your work to a lot of the people I work with and they could not believe it.

Hi OzDragonFlyer,
I am going to by some two flute carbide router bits this weekend and make some test cuts at different router rpms, cutting speeds, and depths. I have drawn some squares about 4x4 in. to cut in MDF. Maybe after a dozen or two cuts I'll narrow the combination down. MDF cuts, drills, routes, and sand good using hand tools. This is probably do to the fact that I'm a lot faster than my cnc router. The faster my router will cut is 17-1/4 imp. I using 1/2x13 all thread for lead screws but will soon up grade to real lead screws and hopefully maybe double my speed.

I need to lenghten my wire going from my controller to the steppers in order to make a neater installation. What would be the best wire and connectors to use?

I brought my steppers and controller from Dave at HobbyCNC and I'm real pleased with the equipment. My controller has the resistors and I read where the new controller does not. Has any one upgraded from the resistor equipped controller to his new one? Is there any increase in performance or does it just do away with the resistor heat?

Gary

Gary,

No sure of the operating voltage you are using, but I'm sure you'll see an increase in performance. In fact, at 44VDC the performance will be sparkling!


Dave Rigotti

[crankorgan]

Gary,
The one percenters are people who finish a machine. I have a private conference for people who bought my plans.

Cranky

[ger21]

Re MDF: for me it's a drill bit killer. I happen to drill a lot of 3/4" holes in 3/4" MDF, an $8 3/4" spade bit lasts for only 24 good holes, and 30 holes if I get too lazy to put in a new bit. I'd sure like to find a real good bit for this, but the more expensive ones I've used don't last much longer...I'm sure somebody makes a superbit, I just don't know who.

http://www.amazon.com/exec/obidos/tg/detail/-/B00004RK59/qid=1098276976/br=1-14/ref=br_lf_hi_14//002-2285274-9465668?v=glance&s=hi&n=575758

Make sure you don't spin it too fast and start burning it, and it will last a LONG time.


Gerry

[CraigF]

Thanks for the info. I suspect I do go too fast, judging by the glue smell, though no obvious burns.

FWIW, this is the most interesting thread I've read anywhere about anything. For people who like gizmos and gadgets and building stuff. Wish I had one of these 30 years ago. A whole different building paradigm, have to look at things differently. Can build stuff that just wouldn't have been practical time-wise before.

[uscra112]

Yah, CNC machine tools have completely changed the world of manufacturing. My pet example is the overhead-cam four-valve engines we can buy so cheaply today. Making the molds for the castings is nearly impossible without CNC machines. There were 4-valve OHC motorcycle engines in 1912, and aircraft engines in 1919, but the cost was too great to put them in cars until CNC came along. Full-scale aircraft parts in carbon composites would be impossible without CNC tape layers. And on, and on.

[balsaman]

Hi balsaman,
I had down loaded a plan (DXF) a few month ago from him and look at it in Autocad. I really didn't know a lot about dxf files or in using Autocad at the time. I just remember the drawings with deminsion lines and such on the plans. I knew that with all of the other info on the drawings that I would not be able to use them like they were. I need to get the file back out now and have another look to see if it is drawn in different layers and if I need to explode the drawings and seperate the parts into seperate files

The drawings can't be used as is. I converted mine to imperial, since that's what my machine cuts, also I deleted all the lines but the outside profile and the center hole of the gears. I changed the inside holes to fit imperal dowel sizes. I drew my own custom spokes. I made my own "boss" near the outside circumference. (for looks only)

I believe everything was all on one layer.

I cut a few things twice (three times?) before getting it right.

Eric

[Krashlnd]

Anyone know anything about John C Kleinbauer's plans called Morph?
I was wanting to know if this one is a good one for a newbie?
Any input would help.
Krashlnd

[Gary Blaylock]

Thanks balsaman.
When you cut your gear teeth, are you cutting in one pass or using several passes? Also, do you machine both sides of your gear by flipping the gear over and keying to the center hole and indexing the gear back onto the table with a dowel or pin?

Hi Dave,
I brought the kit with the 120 oz steppers. I built the controller with the case and transformer you specified in the kit. I think I'm running 24 volts but will have to check when I go back out into the shop. If the new one runs any better than this, it must really be something! If I brought the new controller, will it fit in the case I have now or will I need a new one? What type of wire do I need to get to extend my stepper wires?

Hi Cranky,
Just wanting to join the One Percent Club since I have mine up and running!

Gary

[balsaman]

I cut them in one pass from one side only. The face of the clock above was cut on both sides. I don't remember how I keyed it.....musta drilled a couple holes...

Eric

[Thermal Miester]

OK, I got my plans today from JC Cranky. Look very good. Lots of parts to make, will probably take till February to start messing with the software etc.
I can see why there is a 1% club. For instance, of my Discuss Launched Glider group, about 16 people, only 4 of us build our planes from scratch. Everybody else flies Encores. This CNC thing looks lots harder, except for the flying, which is pure fun.

AB

[Krashlnd]

Well My brain is working overtime on this one. Has anyone built the 3 axis router from Hobby CNC? I am in the process of going through it and getting a grocery list to take to the hardware store tomorrow. This is gonna be great. The wife had already threatened to hide the cash and credit cards :eek: .
I am new to this and Id like to have any information that your brains can dish out.
Thanks krashlnd

[Photon]

Well My brain is working overtime on this one. Has anyone built the 3 axis router from Hobby CNC? I am in the process of going through it and getting a grocery list to take to the hardware store tomorrow. This is gonna be great. The wife had already threatened to hide the cash and credit cards :eek: .
I am new to this and Id like to have any information that your brains can dish out.
Thanks krashlnd

Do you intend to cut Depron with it? (for the F-18 or F-15)

I wonder if the carbide bits will work well on this material too.

[hcjets]

For those of you who purchased Cranky's plans need a source for the Delrin items, you can try - http://www.interstateplastics.com - click on MATERIALS, then click the red shopping cart by Delrin. You will have to scroll down to almost the bottom of the page before you can reach their ordering form. They will even pre-cut to the size you need and the pricing is not too bad.

I'm getting ready to start building my Phoenix CNC machine from Cranky's plans.

JR Gautreaux

[Coligny]

Cranky,

I am looking at building my 2nd cnc router. I need longer X and higher Z, BUT more accuracy.
I used pipes and whls before, but now I think of correctd shaft, with either linear bearings/or bushes.

Q1: Would the drag be to high on bushes? I see few machines utalising this, although I had good success with my foam cutter.
Q2: Should my gantry be stable enough, could I drive it with one rod down the middle. At the moment I use 2 rods, connected with gears and a chain to sequence them. A lot of parts and drag and inertia. I do not like it. If I could use one rod in the middle, I could use double the size (for greater pitch) and still have less inertia (no gears and chains)

I ask you because you have build many, and probably have tried many of these things.

Regards

Coligny Marloth
South Africa

[crankorgan]

Coligny,
I have built 30 machines. All using simple hardware. You need some THK type rails and bearings if you need high accuracy. As for drive a centered leadscrew is the simplest.

John

[Krashlnd]

I just want to be able to cut balsa and lite ply. Yea and even depron if possible. I want to have some help with the construction of this hobby router. I am legit here is the serial # for the plans from hobby cnc: 1787
Thanks hobbycnc for the great service. Anyone with pics of this router please pm me if its ok to share the photos. It is ok right Dave Rigotti?



Do you intend to cut Depron with it? (for the F-18 or F-15)

I wonder if the carbide bits will work well on this material too.

[Krashlnd]

Where did everyone go. All that reading and it stops here? :eek: I would love to have some help with HobbyCNCs plans. Just small questions. Didnt mean to scare everyone off. :D
Krash

[crankorgan]

Krash,
There is also a HobbyCNC conference off Yahoo.

John

[Coligny]

Thanks, John

Thats what I need to know, My first design had only a center leadscrew, but someone convinced me it will not work, and I went for 2, works, but what a complicated energy consuming mess.
High accuracy are relative to what one will be doing. I will be happy with 0.5 mm.
Do I need THK type rails for this?

Coligny

[crankorgan]

Coligny,
I would go with those THK bearing blocks and rails over bushings. Roller Blade bearings on drill rod can be made very accurate with the correct design. Bearings of any kind over bushings. I gave bushings several tries all ending in failures.

John

[Krashlnd]

I do wish Id have bought your 7th plans now. I am gonna try to mod hobbycncs plans to allow me to use the 1/4 x 20 thread rod. Also I need a 24 inch Y cut area. Man How I wish I had went with your plans. Again thanks John for all the posts you have given us.
Krashlnd

[Krashlnd]

I do wish Id have bought your 7th plans now. I am gonna try to mod hobbycncs plans to allow me to use the 1/4 x 20 thread rod. Also I need a 24 inch Y cut area. Man How I wish I had went with your plans. Again thanks John for all the posts you have given us.
Krashlnd

Krash,
There is also a HobbyCNC conference off Yahoo.

John

[Krashlnd]

Oops My bad. Comp locked up and didnt check to see if the 1st post went.
Gotta love Computers :rolleyes: Or the operator :eek:
Krashlnd

[crankorgan]

Krash,
The HobbyCNC plans use more expensive parts. The design requires more skill from the builder. I put adjustments everywhere on my design because I lack real tools here. With the HobbyCNC plans and the info here you should be able to make a hybrid of the two designs.


John

[Krashlnd]

yea looks like that is what I am gonna try to do. Id like to use 1/4 x 20 thread rod and the cutting board nut. maby a few other mods. Hopefully I can get this thing to go smoothly. Ill post pics of the progress.
Krashlnd

[Tim H.]

Where is the best source of small dia. cutting bits?

Tim

[Coligny]

Coligny,
I would go with those THK bearing blocks and rails over bushings. Roller Blade bearings on drill rod can be made very accurate with the correct design. Bearings of any kind over bushings. I gave bushings several tries all ending in failures.

John


For cost I want to try roller blade bearings. The prob remains a accurate shaft/pipe to run them on. I have used stainless pipes before, but they are not perfect. I guess I have to spend money on corrected shaft. Prefferably supported on a rail of some sort. There are so many ways to do it, just that one does not want to waste money. The other option is always to improve my existing machine.
Thanks for clearing the points on bushes, and the drive rods. That already cuts out many options,

Regards

Coligny

[balsaman]

3/4" drill rod is a pretty good option for rails and not too expensive.

Eric

[Tony H]

I figured this thread has the folks most likely to help me find a specific router bit.

What I need is a 1/4" shank flat bottom bit that will project out of a laminate trimmer sized router about 2-1/2" and have 2" of cutting length. That probably means a bit about 3-1/2" long overall. (It will be used to route 2 psf foam thru a guide mask.)

Be nice to have the router portion be 1/4" diameter too.

Any ideas? I've about run out of ideas on how to look for one.

Thanks in advance.

Tony Howard

[Krashlnd]

Hey Balsa man,
Do you intend to sell the plans for the cnc that you have built through this thread or maby email me the specs. I will most defiantly paypal you money for them if you are willing to sell. I did buy the plans for hobbycncs but I kinda like yours better. Only bad part is I bought the lumber for the hobby cnc. Oh well Still would love to have one like yours :D.

[Krashlnd]

Or even If someone has built the HobbyCNC design and would like to share some comments about it. Even pictures.
Steve

[ger21]

I figured this thread has the folks most likely to help me find a specific router bit.

What I need is a 1/4" shank flat bottom bit that will project out of a laminate trimmer sized router about 2-1/2" and have 2" of cutting length. That probably means a bit about 3-1/2" long overall. (It will be used to route 2 psf foam thru a guide mask.)

Be nice to have the router portion be 1/4" diameter too.

Any ideas? I've about run out of ideas on how to look for one.

Thanks in advance.

Tony Howard


http://www.vortextool.com/standard/productDetail.cfm?groupID=277

Part #4135

Although $65 each, if you buy 2 they drop to $45. Just add 2 to your cart to see the discount.

Gerry

[balsaman]

Hey Balsa man,
Do you intend to sell the plans for the cnc that you have built through this thread or maby email me the specs. I will most defiantly paypal you money for them if you are willing to sell. I did buy the plans for hobbycncs but I kinda like yours better. Only bad part is I bought the lumber for the hobby cnc. Oh well Still would love to have one like yours :D.

The problem is my design uses expensive parts that I was able to get free. Download the plan here: www.e-zflight.com/files/cncplans.zip

It's a very basic plan that I used as a starting point. No details to speak of.

Eric

[Krashlnd]

Thanks Verymuch. No offence to the owners of CNCHobby Forum un yahoo but there is nothing there worth while.. Opinions are free. I wish I had went with Crankys plans. If cranky is reading this I have a small question? Do you still not like Gantry style CNCs? Too me It looks like it would put alot of strain on the stepper motor. Is this correct?
Thanks
Steve


It's a very basic plan that I used as a starting point. No details to speak of.

Eric[/QUOTE]

[crankorgan]

Krash,
The leadscrew (threaded rod) amplifies the motors torq. As long as the gantry is not built too big it will be useful for balsa and light plywood. Most people are adding my Centering Blocks to their creations. This allows the rails to be adjusted and a Gantry style easier to make. Making the Z axis too high is a sign of a bad design. Stay withing a 2" Z axis cutting distance and the machine will be more rigid.

John

[balsaman]

You can't strain a stepper motor (other than over current). All you can do is stall it, which doesn't hurt it one bit.

Eric

[Tony H]

Gerry

thanks very much. Exactly what I am looking for. I can't imagine how I overlooked that firm in my searches.

If no one comes up with a cheaper alternative the price is manageable. Carbide should last a good long time in this application.

Tony

[OzDragonFlyer]

a little misleading cranky.. agreed that overall a knee style mill will be more rigid, but it's still possible to have the same stiffness in a gantry design.. My gantry router table is as much at home cutting metal as it is cutting wood/plastics, with 8" of Z travel it still gets ~0.1mm accuracy in aluminium at normal feedrates (much better if I slow it down though)

And it's still not as good as the multicam gantry routers which I've seen cutting 10mm thick aluminium boat parts 24/7 (I want one of these..drooool) :D

[crankorgan]

Oz,
I am talking homemade machines out of MDF or Plywood. Steel and aluminum flex alot less, but even they flex if used in a poor design. I have seen very few correctly designed machines in the last few years. The design flaws usually come about by the greed of the builder to have a larger cutting area or depth than the design can handle. Then there are the Bind-O-Matics. They jog well but bind and jump during heavy cuts.

John

[OzDragonFlyer]

lol bind-o-matics.. sounds very much like my first cnc router! About the only thing it would cut was air (and only if the barometric pressure was low) :)

[HobbyCNC]

lol bind-o-matics.. sounds very much like my first cnc router! About the only thing it would cut was air (and only if the barometric pressure was low) :)

Laughed out loud! I'm gonna use that line some day with your permission?

Dave Rigotti

[crankorgan]

There are Leadscrews and then there are Wavescrews. As the machine gets longer so does the Leadscrew. In order to get the machine to jog from one end to the other in a reasonable amount of time the Leadscrew has to be turned faster. Then it happens! The long Leadscrew starts to bow and contract in the center as it spins. This causes waves to flow throughout the leadscrew. A $100 worth of Leadscrew becomes a bad purchase. Don't let the wife know!

[Lachlann]

Hello everyone!

I found this discussion thread off a link from Cranky's site, and it has taken me 2 whole days to read it! (ok, ok, so I skipped over the g-code messages. I'll go back and read those later.)

I've been wanting to do home CNC for a long time, and like most people have not had the money to sink into purchasing a complete machine.

I have to say - this forum is great! I've ordered Cranky's "Brute" plans, and plan on starting on my own machine next week.

I know I have some questions, but I'll comb back through the forums and make sure they were not answered (and wait until the post office has delivered my order to Cranky - mailed yesterday from Apex, NC) before I start asking. :D

One thing all of the airplane hobbiests might be interested in.... I know people have mentioned laser cutting. Although I have not tried one of these systems (and they are $10,000), they might be something to drool over.

http://www.versalaser.com/english/

[Coligny]

Stupid question, what is a drill rod, and where does one get, or what do they normaly use it for.

Thanks

Coligny

[crankorgan]

Drill rod is straighter-smoother and harder than the solid cold rolled rod found at Home Depot. You can buy drill rod at your local industrial supplier or online. Drill Rod is harder than cold rolled but it can still be cut with a hacksaw.

[Krashlnd]

That Been my problem. Locating drill rod.
Krash

[Coligny]

If I could tell suppliers the usage, they could perhaps tell me what it is called locally.

[Coligny]

Another Q:

On a 1/2 " lead screw, what would be a acceptable x axis travel, before I get a "wavescrew"

[rcav8r2]

That Been my problem. Locating drill rod.
Krash
Try http://www.use-enco.com I get a script error when doin a search or I'd post adirect link. I know they have it as it's in my print catalog.

[Bob H]

Hey goys, take a look at www.onlinemetals.com I have had good service when I ordered from them. Just a suggestion Bob H

[crankorgan]

Drill rod gets welded to the back of a drill bit to make it longer. It has many other uses but it is called drill rod. Many places sell cold rolled which is now made in China and is junk.

[ger21]

Another Q:

On a 1/2 " lead screw, what would be a acceptable x axis travel, before I get a "wavescrew"

If you're using acme, go to http://www.nookind.com and download their acme catalog. It has a technical section with charts showing how fsat you can safely spin the screws. The call it critical speed, and it depends on length and how the ends are mounted.

Gerry

[Coligny]

Thanks, I will look for it here in Soutf Africa,

Anyone with experience with stainless tube?

[Dongledell]

Hi all,

Decided a couple of days ago to make a CNC and came up with a design, then a mate pointed me at this thread! been reading steadily - up to page 20 or so so quite a long way to go! just wanted to ask a couple of questions while I read as I need to order some ally for my machine.

Firstly - my design uses box section ally tubes as rails, mounted at 45 deg with castors that fit over the corners top and bottom (taken from a popular design of cross cut saw) before I get the tube, has anyone tried this and encountered any problems?

second question - when cutting things in 3D, how do you get around the stepped pattern in cutting complex curves? Is it simply not possible with this sort of machine and code, or can I make the tool tilt and swivel (adding an extra 1 or 2 axis?) so smooth it (or is there a simpler way?!)

Sorry if these are already answered - dont get a lot of time to read and it's going to take me till past christmas to catch up on this thread!!!

[uscra112]

I'll answer the question about steps. You always have them. Even with ultra-expensive 4 and 5-axis CNC machine tools, the airframe builders still get them. They sandpaper them off. Honest. I've watched it being done - I spent almost 2 years at Fairchild Republic when they were building the A-10. Also I was methods engineer when we machined 200 aluminum landing legs for Blackhawk helicopters in 1993, on 4-axis machining centers. One thing that reduces them however - use ball-end mills.

[Dongledell]

well that will certainly save a bit of construction and head scratching time on this machine then :D cheers for that.

[RJG]

Hi folks,

does anybody here know if Turbocad designer 2D/3D 9.1 is sufficient for creating files for import to Turbo CNC?

Also, will Turbocad designer 2D/3D 9.1 alow me to import and export *.BMP, and *.Jpg files?

[DICKEYBIRD]

TurboCAD will definitely output in the .dxf format and if your TurboCNC program accepts .dxf's the answer is yes.

TurboCAD accepts quite a few raster based graphics formats so yes, .bmp's and .jpg's will work. It will not modify a raster image but it will allow you to trace over them with vector entities or do a crude raster/vector conversion. So the answer is no to the "export" a .bmp or .jpg question.

I have old, slow computers and still use T/CAD v3.12 (harkens back to Windows 3.1) and all the above functions work fine so I'm sure the much later version you mentioned will do great.

[ger21]

Hi folks,

does anybody here know if Turbocad designer 2D/3D 9.1 is sufficient for creating files for import to Turbo CNC?

Also, will Turbocad designer 2D/3D 9.1 alow me to import and export *.BMP, and *.Jpg files?


You'll have to export .dxf's from TurboCAD and use ACE to convert them into gcode that TurboCNC will use.

[Dongledell]

Couple more questions for you.

Although I haven't got the machine ready I am looking for the various bits and bobs for it, but not really sure what's needed in most of the departments! what's the minimum specs I should be looking for in the stepper motors and boards?

Also, does it matter if the stepper motors are not all the same, or would it be best to get 3 identical motors?

Many Thanks

[Bonxy]

Hi all
Just want to ask a simple question.
Looking at the posts it seems that a lot of you guys are using the cheap threaded bar such as you would buy at B&Q for about £8 to move the axes, is that right ?

Thanks

[planeflier]

I see that some people are using a 4th rotary axis. how are you guys programming this for cutting?

[reeferjon]

Well this thread has took some reading.. Its definitly a hobby on its own.
My question is.
Does the UK have anybody who generates plans or kits that match the standards of equipmnet discussed within this thread.
Thanks

[new flyer]

hi guys i have autocad and know how to use it. i know how to build the table with the motors and stuff but what program and hardware would i use to change the autocad drawings into somthing that the hardware can recognize and tell the steppers to do. i know everything but what harware and software to use to contolr the steppers.can anyone help.

ps anybody know if a dremmel would cut zepron foam very good or would it make crappy cuts. would it be better in high speed or low

[furyflyer2]

Well this thread has took some reading.. Its definitly a hobby on its own.
My question is.
Does the UK have anybody who generates plans or kits that match the standards of equipmnet discussed within this thread.
Thanks

their is a free plan here-
http://www.cnczone.com/forums/showthread.php?t=6054&highlight=free+plans

[thrmaln]

Hello all,

I keep tabs on this thread from time to time and see all of requests for leadscrew information and calculation info. Anyway, I am a Linear motion stage designer and have an excell file that may be of use. It is based on Kerk motion proprietary screws, but it will work for any Acme threaded screw. If used for screws other then Kerk you will need to cross reference kerk's series number and enter it in the required field for the diameter and lead that matches the one you intend to use.

I also included jpeg of a Z axis wedge stage. The leadscrew cover has been hidden to show how it works. The Leadscrew drives the middle wedge which causes the upper plate to translate upward. The upper plate is held in allignment by some linear bearings that change the horizontal movement to vertical.

Hope the file helps,

Best regards,

Marc Webster

[OzDragonFlyer]

How does this arrangement overcome the friction between the 2 faces? Interesting idea!

[thrmaln]

Hello Ozdragonflyer,

To answer your question, there is very little friction at all; almost zero. The picture does not show it, but there are linear bearings that seperate all three sliding plates. They look like the two bearings set verticaly in front attached to the pink tee shaped piece. The green blocks are what would be called trucks and the gray rail is the bearing track. The bearing trucks have channels in them that mate up to channels on the rail. There are two channels per side. One on top and on bellow which lock the truck in place with absolutely no slop in any direction. As the truck moves the ball bearings recirculate from onside of the channel to the other from front to back or vice versa based on direction which allows the rail to slide.

Here is a spec sheet that may help: http://www.thk.com/archive_file/technical_dl/pdf_en/A262-287.pdf
I am using the HSR8 rails

The only friction would be having to lift the weight of whatever is on top of the upper wedge. The mechanical advantage of the ballscrew (in this case) coupled with the fact that I only need to translate a wedge with a 15 degree angle makes the lift even easier. However if the weight is too high and my ballscrew has to low a pitch it can backdrive when the motrs turn off. Usually the motors stay on at a reduced current when the stage needs to hold position.

Hope this helped,

Marc Webster

[OzDragonFlyer]

I'm familiar with linear motion components.. so you are saying that the wedges have recirculating grooves cut into them? Then the ball bearings would move across the faces of the mating wedges when the 2 parts slide together? Neat idea.

To reduce the backdrive , it would be possible to gear the servodrive down, giving the motor a mechanical advantage at the screw. This is a simple method I used with my cnc router, especially on the heavy z-axis where there are large vertical loadings on the screw.

[thrmaln]

Hello Ozdragonflyer,

The wedge plates themselves do not have the recirculating grooves cut in them. The bearings are a unit that has 2 trucks and 1 rail per side. The bearing assembly just drops into place where I have made recesses for them to reside. I have posted another picture with the top plate hidden that shows the bearing assembly for the upper plate. Hope this helps. If you look at the attached website mentioned in a previous post it shows how these bearings work.

As far as gearing down the screw, that would not be a good idea. The problem is any gear assembly will introduce backlash and this stage has to be repeatable in height to microns. The ballscrew I use is preloaded and has absolutely no backlash. This stage goes into a high end electron scanning microscope. The best way to prevent the backdrive is to tighten up the pitch of the screw less lead per diameter = less backdrive. On a wedge stage it is different but for regular linear motion in a dead lift Z application there is a rule of thumb that generaly works to prevent backdrive. You need a 3 to 1 ratio (lead/dia) for uncoated screws and a 4 to 1 ratio for teflon coated screws. An example would be for a 1/2" diameter Acme thread teflon coated screw, you would not want a lead any more then 1/8"' per rev.

Best regards,

Marc Webster

[OzDragonFlyer]

ahh now I see.. I used to use SE microscropes in a research facility I used to work at, never imagined the stage was raised and lowered this way. That's quite a lot of engineering!

My z axis screw is 10tpi teflon, but I could still rotate it if I pushed hard down enough on the slide. I geared it down using a toothed belt which cured the problem (seems to stop due to the cogging effect of the servomotor )

That's a nice assembly btw, are you using solidworks? Was it a difficult to get simulated movement from the screw to the wedges? Impressive stuff.

[Toywizard]

Hello all

I am checking out the Taig CNC milling machine for a home business, never mind the RC stuff that I could do with it.

The 2027 with 4th axis rotary looks like the direction for me to go in but has anyone had any experience with this machine?

Thanks in advance.

Scott L Golden

[C. Alan]

I have been reading this thread, and I am wondering if a home built cnc machine would work for me.

I mainly build park fliers with wingspans around 30", and I use a lot of 1/16 and 3/32 stringer in my construction. Could a home cnc machine be set up with the kind of tolorance that would allow for a 1/16" slot be cut in a rib? Do the make bits that go down to 1/64" or 1/32"? I have noticed that most of the people us 1/8" bits, and that would be fine for most parts, but to cut ribs and formers.... hmmm..
--C. Alan

[balsaman]

I have used 1/16" bits and they come smaller. Much smaller.

Eric

[balsaman]

http://www.thinktink.com/cgi-bin/carbide.cgi?page=stubmill&step=20&start=0

[C. Alan]

Thanks,
I think this board is about to get me in trouble with my wife again....
--C. Alan

[madmike8]

Well I just completed reading the 154 pages of this thread... I feel like I've run a Mental Marathon... You might want to cancel any flying plans this weekend. Mrs. Myers my Fourth grade english teacher said Pigs would fly before I ever read this much, and I never knew her to tell a lie... So be careful... :D

I've already ordered John's (Cranky) 7th Plans, and hope to be able to contribute to this thread in the future.

I'd like to Thank all the folks that posted in this thread for all the wonderful information you made available here.

[TimKoene]

Turbocnc is giving me the finger.

I have designed and built a servo controller for my pcb machine to be. When I hooked it all up to my old P120 with turbocnc, it does not work. After some frustration and shouting, I decided to go back to basic and check the output of the P port with leds and a scope.

I have found that the STEP signal of my turbocnc (the latest version, dl'ed a month ago) is messed up, even with the standard ini that comes with turbocnc. I have tried every pin available, and combinations thereof, but it seems software. The dir signal is clean, crisp, and does what it it supposed to do, but the step signal remains high forever. The ports work, I have checked that with the port monitor and my own programs.

I am testing this all with jogs, and currently on pin 5 and 6, but like i said, I tried it with other. The step signal refuses to go low. It is one continuous signal, I checked it with a Fluke Digital Scope. I have no clue what the hell is wrong.

Now, what could be the problem, the computer works, the software is the same everyone is using, and the leds are quite quite normal too. ;)

What the heck is wrong?

[crankorgan]

Try running CNCPro for testing. If that works go from there. If the Direction was also not working I would say you had the wrong printer port selected but that is not the case.

[ger21]

Turbocnc is giving me the finger.

I have designed and built a servo controller for my pcb machine to be. When I hooked it all up to my old P120 with turbocnc, it does not work. After some frustration and shouting, I decided to go back to basic and check the output of the P port with leds and a scope.

I have found that the STEP signal of my turbocnc (the latest version, dl'ed a month ago) is messed up, even with the standard ini that comes with turbocnc. I have tried every pin available, and combinations thereof, but it seems software. The dir signal is clean, crisp, and does what it it supposed to do, but the step signal remains high forever. The ports work, I have checked that with the port monitor and my own programs.

I am testing this all with jogs, and currently on pin 5 and 6, but like i said, I tried it with other. The step signal refuses to go low. It is one continuous signal, I checked it with a Fluke Digital Scope. I have no clue what the hell is wrong.

Now, what could be the problem, the computer works, the software is the same everyone is using, and the leds are quite quite normal too. ;)

What the heck is wrong?

Did you try changing the pulse width? If that doesn't work, I'd say it's either you have some other settings wrong, or your port is bad. I'd lean toward the first.