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Sep 30, 2014, 08:42 PM
AndyKunz's Avatar
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It was a good evening for getting some work done on the laser cutter tonight.

I started by mounting the X rail. Note that the right trolley is not symmetrical, as shown in the photograph. You have to get it the right way, so it matches the left side (which you can only do one way). The rail isn't symmetrical either, so it's easy to get them together properly.

I put these on with M4x16 bolts. I'm still waiting on Marco to relay information from China regarding the intended bolt lengths. I use 16mm here because the 11mm ones don't extend all the way through. You want maximum strength here, so the extra 5mm makes sense.

Tighten down the slider guides as well. They need to be perfectly parallel to one another. I did this by measuring and snugging, then running the gantry several times back and forth across it. Then snugging tighter, and repeated a few times until it moved nicely. I'm open to suggestions on better ways, but this worked for me.

Next I added the two Y belt idlers for the front of the machine. These need to be parallel to the drive ones on the far end as much as possible so that the belt is not twisted or stretched.

After that I added to X motor bracket. This was mounted with M4x11 bolts since I ran out of M4x16's. The X idler is attached to the far end using M4x16 bolts.

Andy
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Sep 30, 2014, 09:04 PM
AndyKunz's Avatar
Thread OP

Time for belts!


The two Y belts slide into the rail easily. At the back you need to pull it through and thread it under the drive pulley.

The belt is captured on the trolley. The front side (where the laser beam will be) is connected first. You will have a little excess, and you don't want that flopping around the side where the laser head will be moving back and forth. It must be centered to the pulley and squared.

Note in the photos how the tensioners are threaded out a little. You need to do this so you can tighten the belt later.

Next, the back side is attached. There is a little excess here, and it just curls up out of the way. Later on we can trim it because belts stretch, not shrink. It needs to be squared as well.

Now you can tension the belts, but don't over-tension them! I set mine for about 1/4" up/down play. You don't want it to be too tight because that will just wear things out sooner. The motors will overheat and die early, the belts will loosen, and you won't gain any accuracy.

After doing both sides like this, we need to tie them together. I slid the X all the way to the back of the machine, then tightened down the couplers (they've been loose to the drive pulley all this time, I think I mentioned that earlier).

While setting up the X belt I ran into a little snag. I'm waiting for an answer from Marco before I can continue.

Andy

PS. This is a great community! As I was typing about tensioning the Y belts, Cherokee Flyer PM'd me about making sure the belts aren't too tight. I appreciate having more-experienced folks looking over my shoulder - if you know more than me (not hard ) please speak up so others aren't misled, and so I don't do stupid stuff to my own machine! Thanks!
Oct 01, 2014, 09:15 AM
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LesUyeda's Avatar
"You want maximum strength here, so the extra 5mm makes sense."

Out of my past life (in engineering), I learned/was tought, that once you have thread length equal to diameter, no more strength is available. Extra length does help keep nuts from falling off if things loosen up.

Les
Oct 01, 2014, 09:31 AM
AndyKunz's Avatar
Thread OP
If the thread doesn't go all the way through the metal (nut) you are losing strength. That was my reason. Thanks for asking. The 5mm longer ones are only 2-3mm longer than to the edge of the metal.

Andy
Oct 02, 2014, 10:17 AM
AndyKunz's Avatar
Thread OP
It's going to be a week or two before I can do very much more on the X axis.

I have to return a part to LightObjects that was made incorrectly. In the meanwhile I will work on integrating the XY onto the frame, getting the shelves and electronics in place and wired, etc.

There's still plenty of work to do, but it will be in a slightly different direction.

Andy
Oct 02, 2014, 08:40 PM
AndyKunz's Avatar
Thread OP
Before taking off the parts I need to return to Marco (who is graciously cross-shipping the replacement to me), I decided to take photos of the limit switches. These will provide a "home" position to the controller so it can reliably start from the same place every time it cuts.

The switches are part of the XY kit, as well as the bolts to attach them. As noted earlier, the completeness of the items has been exactly as expected with even a few spares.

The X limit mounts on the top of the X rail at the right end. The geometry wasn't exactly what I would have liked, as it requires the trolley to slide against the metal rather than on the roller, but it does cause it to flip the switch as needed for operation. Perhaps I'll take advantage of the down-time to change this to suit my preference.

The Y limit mounts in the left rear corner of the system on a side rail. Mounting it using the provided hardware, it would not go down tightly because the lower angle bracket pushed against the electrical contacts. I solved this by getting some bolts 4mm longer which will allow a small gap. The contacts will have heat shrink over them for insulation, but there's no sense having the insulation pinched - it'll just wear through eventually. If it ever does, this will be a simple fix, though.

Andy
Oct 02, 2014, 10:26 PM
Play that funky music right
kenh3497's Avatar
Quote:
Originally Posted by LesUyeda
"You want maximum strength here, so the extra 5mm makes sense."

Out of my past life (in engineering), I learned/was tough, that once you have thread length equal to diameter, no more strength is available. Extra length does help keep nuts from falling off if things loosen up.

Les
An "old" tool and die guy once told me that 1 1/2 bolt diameters was all you needed for maximum strength. I do admit he was talking about threading into cast iron at the time. IMO, two bolt diameters in aluminum will be just fine.

With the above said, if having the bolt run the full depth of the thread makes you feel more comfortable, then use the longer bolts.

Ken
Oct 03, 2014, 08:23 AM
AndyKunz's Avatar
Thread OP
We're saying the same thing.

If I have a M3 bolt that is going halfway into 5mm thick aluminum, that's not enough. It needs to be longer to get a full SINGLE bolt diameter.

Andy
Oct 03, 2014, 09:19 AM
Registered User
LesUyeda's Avatar
"An "old" tool and die guy once told me that"

Used to love boxing in those "old" tool and die guys by tracing back their knowledge base. It was typically another "old tool and die guy" that told another guy that told another guy:-)))))))

Absolutely no science at all.

Les
Oct 03, 2014, 12:24 PM
Illegitimi non carborundum
grosbeak's Avatar
In many cases, experience is an acceptable substitute for education.
Oct 03, 2014, 12:51 PM
AndyKunz's Avatar
Thread OP
In other cases, it's superior to one.

And in many cases, it's absolutely necessary!

Andy
Oct 03, 2014, 03:49 PM
Registered User
LesUyeda's Avatar
I fully understand the value of experience. I just would not care to bankroll a group of people that were only learning by experience. I would not like paying for their mistakes.

Andy, I'm not sure where that applies. Could you give me an example???

Les
Oct 03, 2014, 04:23 PM
AndyKunz's Avatar
Thread OP
Quote:
Originally Posted by LesUyeda
I fully understand the value of experience. I just would not care to bankroll a group of people that were only learning by experience. I would not like paying for their mistakes.
Agreed! We call them "interns" around here ...

Quote:
Andy, I'm not sure where that applies. Could you give me an example???
Not sure which "it" you mean. Assuming you mean to ask where I think experience beats education it would be anywhere that skills are needed. I wouldn't want to pay for somebody getting experience only by doing, but I sure wouldn't want to have somebody doing something requiring skill (creating software, for instance, or doctoring, or piloting) who had only book-knowledge and no practice. That is, both are needed.

If you mean where education is absolutely essential (what I meant in my final sentence), I would go with doctoring, creating software, and piloting...

Andy
Oct 03, 2014, 05:28 PM
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Cherokee Flyer's Avatar
Didn't we all start as "interns" in one form or another?

L.
Oct 04, 2014, 09:23 AM
Registered User
LesUyeda's Avatar
Someday, maybe, I will learn how to communicate; maybe:-))))))))))))

"In other cases, it's superior to one."

This is the "it" I was referring to.

Les
Oct 04, 2014, 09:34 AM
AndyKunz's Avatar
Thread OP
You know what, Les. It's probably ME who wasn't communicating well. It is such a bad word to use when there are two possible things which could be referred to!

Andy
Oct 04, 2014, 06:07 PM
AndyKunz's Avatar
Thread OP
Quote:
Originally Posted by AndyKunz
The next step is to square up the frame. In trying to do so, and keep all the items at right angles to one another, I found what I consider to be an error. The part "e" is 5mm too long. Marco insisted that it's correct, but I don't see how and I did the math several times to verify. Whatever - the solution is easy!

In this photo you can see how the one part is offset from the center (by 5mm, coincidentally). I removed the corner brace so that the vertical part could be perpendicular. Once I did this, the entire rest of the frame just harmonized itself.
It's autumn, and autumn means pies, so it looks like I'm going eat a little - humble pie, that is.

Marco was correct. So was I, but not for the reason I thought.

Back in post 12, I built the E/K assemblies. I assumed because of how the CAD was drawn that they would be built at the full height possible. Turns out, that's not the case.

The two long E pieces are the frames that the honeycomb will rest on. They need to be vertically adjustable (Z axis) to some degree, and for placement of the honeycomb under the cutting area need some adjustability so you can make sure the full 900x600 area is over honeycomb. The XY frame rests on the pieces (D, shown in post 20) that are supported by the two vertical K pieces.

It took a lot of studying of the photos in Marco's build thread to figure this out.

This meant that I had to remove 8 corner braces that connected the two long E pieces to the two D pieces, and then remove the nuts from the rails. That was interesting since some of the nuts were thicker than others and didn't want to rotate so I could pop them out easily. It just took a little extra persuasion to make it happen.

So, with that explanation behind me, I can now tell you that the XY gantry is mounted to the frame. It can be slid back and forth so that there is clearance for the door, the wires in the rear, and the laser tube. I probably won't lock it into the final location until I'm farther along.

There are 2 bolts in each corner that connect the gantry to the frame. Getting the nuts on the bolts in an almost-totally-blind position was a challenge, but one that can be accomplished.

Andy
Oct 04, 2014, 09:58 PM
AndyKunz's Avatar
Thread OP
It feels like progress is happening faster now. That's definitely an encouragement!

I loaded the honeycomb onto its holders, and used corner braces to hold it in place. It's plenty heavy - it's not going anywhere! The braces just lock it so it won't move as the machine positions the heads. Later on, an air chamber will be built under it to provide some force to hold the wood down and to draw off the smoke.

Back at the start, I had several packages of nuts and bolts that came with the frame for which I couldn't determine a purpose. Tonight I found it! The brackets that mount the laser tube, lenses, and mirrors have smaller holes in them than the frame mount bolts. That's where they go.

The rails that they mount to are easy enough to remove, so I pulled them out and loaded the nuts the easy way, then put them back into the frame. The tube mounts are double-high channels, so they can be installed without removing the mount from the frame.

As an aside, I noticed that Marco's build only had one set of corner braces on these pieces, and that it allowed them to be placed closer together. While I had them out of the frame I did the same as well.

I haven't bought a beam combiner yet (it lets you have a red dot target for setting up the wood easier when cutting), but as long as I was doing this stuff I decided to make it easier for myself later. I put the nuts and bolts to mount it in place.

No laser work tomorrow afternoon; I need to replace the kitchen faucet. That should be only a minor thing, right? With my luck I'll spend the whole afternoon and evening on it.

Don't forget to go to church, guys!

Andy
Oct 18, 2014, 03:33 PM
AndyKunz's Avatar
Thread OP
I haven't been able to do much the past two weeks. Marco sent me a corrected X trolley this week and today I installed it and finished up the belts. Then I realized I couldn't go any farther until I had a shelf installed for the electronics. Off to Home Depot...

And, well, they had a Makers Fair not too far away, so I went there for an hour or two...

Needless to say, I haven't gotten much done to show today, but I did have a good day!

Andy
Oct 18, 2014, 07:07 PM
AndyKunz's Avatar
Thread OP
I picked up some nice 1/4" and 1/2" sanded birch ply quarter-sheets from Home Depot to use as the shelves and top. I haven't cut them yet - I'll take the tablesaw outdoors to do that because of all the dust, and that will require a little bit dryer day than today was.

After quite a bit of sleuthing online today to make sure I had the correct wiring I finally wired up the X axis motor to test operation. If it worked, great, but if it didn't it would limit the amount of things I need to replace...

I manually moved the X head to the center of travel.

I powered up the unit and in a few seconds the X motor started heading toward one end, looking for a limit switch. It was the wrong end, so I swapped two motor wires (it's just like the BL motors we fly with) and it homes in the proper direction. It worked!

I'M STOKED!!!

Now that I know the correct wiring, I'll plan out the rest of it and order different colors so I can color-code the assembly. Nothing worse than duplicate color wires with different functions! Yeah, it'll cost a few dollars, but when it comes time to service things I'll not regret a penny of it.

Andy
Last edited by AndyKunz; Oct 18, 2014 at 07:19 PM.
Oct 20, 2014, 04:27 AM
Ground successfully attacked!
GroundAttack's Avatar

Fantastic progress!


Really interesting. I can see that this is a really professional build, just by looking at it. You are so right about spending time now labeling correctly as wires do break and screws do work loose!

Keep up the good work!

Thanks
Martin
Oct 21, 2014, 12:32 PM
AndyKunz's Avatar
Thread OP
The system needs some 2-conductor wires to run to the limit switches. I have a bunch of Alpha 24AWG PVC insulated hookup wire, so I took about 12' of purple and yellow and made my own.

I tied one end together and then onto a fixed object, in this case the latch for the door to my shop. After stretching them out together straight, I tied another knot in the wires and inserted the knot deep into the chuck of my hand drill. For a nice twist it's important that the two lengths be equal and taut when starting.

Then just a few blips of power on the drill and out pops a nice twisted pair of signal leads. Don't spin it too fast. If my drill had a slow speed setting, I'd have used it! That's why the power was blipped in.

Some notes on wire selection here:

1) 24 AWG is fine for low-current signals like limit switches. The motor power leads need to be much heavier. I'll be using 18AWG on them.
2) The PVC insulation is fine for applications where they won't be moving a lot in the cold. Silicone insulation is better for more-flexible needs.
3) The more strands the better for flexible wire! This is only 7 strands of 32 AWG (noted as 7/32 when you're searching). DON'T use solid wire!!

Andy

BONUS FEATURE: A video of the wire being made

Making Twisted Pair on the Cheap (0 min 21 sec)
Oct 21, 2014, 12:53 PM
Surface, Air & Water Rc Toys..
And people find my paint mixer funny.

Homemade Paint Mixer (0 min 16 sec)
Oct 21, 2014, 12:54 PM
AndyKunz's Avatar
Thread OP
Cutting edge technology!!!

Andy
Oct 21, 2014, 12:57 PM
Surface, Air & Water Rc Toys..
Rofl
Oct 21, 2014, 04:29 PM
Registered User
Roguedog's Avatar
Hey Andy.

How are you gona have enough room for your CNC machine with that extra lawn mower in the garage?

I guess u must have some sentimental attachment to the old one. I have the same problem. I've got a 4 burner gas kiln just taking up space. I got it for free, never used it, but just can't seem to get rid of it..
Last edited by Roguedog; Oct 21, 2014 at 04:39 PM.
Oct 21, 2014, 04:32 PM
AndyKunz's Avatar
Thread OP
My son is getting married and buying a house next year. That's his mower. He needs to get it running first

Andy
Oct 21, 2014, 04:46 PM
Registered User
Roguedog's Avatar
It just struck me funny to see two of them.

Following your build closely. Looks good so far.

Good Idea for making your own twisted pair wire. How many twists per inch did you finally get?

As far as mixing small batches of paint I think I'll just stick to shish kabob sticks.
Oct 21, 2014, 04:55 PM
AndyKunz's Avatar
Thread OP
Good question!

When you make your own twisted wire, as soon as you disconnect one end a bunch of turns come out as the wire relaxes. A whole bunch!

Right now I have about 1 turn per inch. After I trim it to length I can go back and tighten it back up, but I think this is sufficient. They'll be run inside the channel or against the frame for the most part. These aren't going to be communication wires, just switch contact closures.

Andy
Oct 21, 2014, 05:15 PM
Registered User
Cherokee Flyer's Avatar
That has worked for many years on the machine tools we used to rebuild. Some of them have been in production shops over 15 years. We did clear up to #10 wire, which I might add took a good Milwaukee 1/2" drill and a well mounted vice!

L.


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