Grunblau Platform CNC build thread - RC Groups
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Jun 22, 2012, 07:58 PM
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Build Log

Grunblau Platform CNC build thread

I realized that even though RC groups is where I first showed the new CNC I was working on in this thread, I haven't been back to post the progress until now.

I am adhering to the adage that people generally end up building more than one CNC. Once bitten by the bug there is no turning back...

For the last couple years, I have been tinkering with the design of a bent steel and aluminum CNC. This method of construction is something I have become pretty familiar with at my day job. I finally settled on the production model and began ordering parts last month.

Here you can see the overall design of the machine. I am hoping to get everything powder coated once the initial build is complete.

I designed the machine with these options in mind: Mill, Plasma, Laser, Extrude, and Tangential Knife. I wanted to be able to pursue these functions at a later date. There is embedded in the design, allowance for a vacuum table or a water tank.

Once I received the steel, I quickly started assembling and test fitting. I had received a small batch of steel a few months ago so that I knew that the design for my linear motion would work before committing a huge amount of $. I also made a wrench for easy adjustment of the V-groove wheels.

A friend gave me a huge old drafting table. After these pictures, I assembled my work surface so that I wouldn't wear out the knees on my pants. Here you can see that I am waiting on a shipment of 80/20 pieces. I had the cross member for a couple years now. I tapped all of the holes and assembled as much as I could.

Whoo-hoo 80/20! Cut to size with all of the holes tapped.

Picture taken about 15 minutes after getting the 80/20

Footprint is approximately 3'X5'

I started to rethink having the G540 in the front. Although it is a nice idea to showcase the $300 part, the logistics of routing the cables back under the table has convinced me that I should get these parts redone and mount it in the back of this 'saddle bag'

I began shopping for a craigslist computer, as I knew I wanted to leave my other MDF machine intact since the milling area is larger. I also felt it was time to get a flatscreen monitor. I found a great deal on a Dell XPS 400 circa 2006 with a 20” monitor.

I got it home and noticed it was lacking a printer port. Oops. Well not a problem, right? I'll head over to Microcenter and pick one up. Not necessarily the case. If you find yourself in this situation, save yourself the headache I went through and buy a Rosewill RC-304 2 port PCI card. Even though other cards list EPP mode, your computer will automatically select ECP mode. Since the add on card is not part of your motherboard, you cannot control this. This card works and is made to work with the G540! My charge pump is on and everything works flawlessly so far.

Click the link below to see the card I bought...

Rosewill Card for G540

This video shows the linear motion before I was able to hook up the leadscrews and motors...

Platform CNC, Linear Motion (0 min 33 sec)

After a bit of thought, I decided to go ahead and commit to moving the G540 to the back of the controller saddle bag. What a difference as far as ease of cable management (I still need to work up a permanent solution).

Here are the new parts...

The simple angles might end up living in the corners of the 80/20. Unfortunately, I do not have any drop-in T-nuts. So unless I get really ambitious and disassemble half of the build in order to install these corners, they will have to wait until after the powdercoater or painter (I don't know if I have the tolerances for PC). I also eliminated the extra fans in the power supply saddle bag. These were entirely unnessesary as the integrated fan moves almost enough air to cool the G540.

Keep in mind this is only the initial fabrication mockup (think American Choppers), the rusty, uncoated steel will be finished and the thin steel uprights, Z plate, and lower cross-member will be exchanged for 3/8” aluminum.

I had no real idea of the benefit of this until I started looking at the numbers...

I could be wrong, but...

Steel ~ 0.29 lbs per cu in
Aluminum ~ 0.095 lbs per cu in

78 cu inches of steel @ 3/16” thick
=22.62 lbs for steel

156 cu inches of Aluminum @ 3/8” thick
=14.82 lbs for aluminum

Thats a weight savings of almost 8 lbs, 2/3 of what it is now.

What about strength?

For a plate in bending, the strength of the plate is related to the cube of the thickness. Aluminum being about 1/3 the density of steel can be at a 9 times advantage based on thickness at the the same weight. This offsets the 1/3 aluminum lacks in strength.

A simple rule of thumb:

Aluminum needs to be 1.5X times as thick as steel to have the same strength.

The aluminum plate at 2X the thickness would be over 2.5X stiffer than the steel at 2/3 the mass!

The bling factor has not been quantified.

Here you can see the rear facing G540 installed.

Compared with the front mounted one...

An issue I ran into was with the locking collars on the Z axis. You can see in this picture, the differences in the manufacturing tolerances from collar to collar...

Luckily, I ordered too many of these so I was able discard the ones made while the QC guy was on his break. Even with the more centered hole, I only have about 1/16” of clearance for these and exchanged the fastener with a button head.

I will likely have to alter the Z-axis linear motion plate to account for this in the future.

When I started this build I wanted to meet or exceed the capabilities of the Rockler Shark Pro...

Based on good and bad reviews of the Shark Pro CNC, I decided to try to use the cost of the Rockler machine as a sort of starting point for constructing a DIY machine. Using the $3500 cost point as a guide, I began designing, but I quickly abandoned the specs of the Shark Pro as they are not that useful to me. I will likely come back to it as an interesting comparison at a later date.

On Sunday, I was able to get everything assembled and configure Mach3. This video is the first test of the motion system. I ran a toolpath @ 200 IPM. I still have some minor tweeking and tuning of the G540. I wanted to be sure to be able to run at this speed at least as there are some materials that like to be cut between 100-200 IPM. I also have to figure out a more permanent solution for a cable carrier. As far as screw whip, it isn't a factor at this speed. I am also slightly tensioning the screws, so a full 6' McMaster span is definitely possible. Would not want to see what the 108” span of my MDF machine would do though. Since I took this video, I have ran it at 300 IPM, with no issues...

Platform CNC, Initial Build and Motion Test 200 IMP (2 min 57 sec)

That's it for now!

I still need to:

Figure out what and how I am going to mount to the Z-plate (hole spacing was based on K2 mounts)
Cut off the lead screws
Order the aluminum
Set up limit and home switches,
Manage cables
Build table surface
Send to powdercoaters

I look forward to any comments!!!


Brian Oltrogge
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Jun 25, 2012, 12:22 AM
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Sort of recovering financially before ordering the aluminum pieces. I am also designing a router mount in hopes of getting that done at the same time. This weekend I crossed a couple things off of my to-do list. I wanted to make a base for the CNC that would put the CNC surface at about 32 inches off of the ground. I might add storage into it at a later date but since I got a notice that I will be at the Detroit Makerfaire in a month, I sort of have to start moving quickly. I hope to get as much done as possible.

Here is what I settled on for the base. Dimensions are 40" X 68" X 20". It is just 3/4" plywood that will get a simple polyurethane and paint finish. I am waiting for the first coat to dry right now, so I thought I'd post an update during the downtime.

Here is the base, pretty simple Kregg jig construction. Finished it late last night at my workplace. Sort of pays homage to my MDF CNC

Then I needed to put together something for the insert. Since I am setting the machine up for milling, a plain old MDF torsion box would do nicely. Planning for a spindle in the future, but I will likely have to make do with my Bosch for awhile.

Here is an exploded view of the insert. I left some notches in the ribs in case I might want to add a vacuum hold down/vacuum forming function at a later date. You can see some initial sketches on the surface if you look hard enough. I milled a series of extra 5/16" holes to receive some 1/4-20 T nuts for fixturing in the future. Any pattern I would end up doing on the top will have to wait for the Platform CNC to cut it.

Amazing how much easier this stuff is with a CNC

Closeup look.

I thought this was an interesting comparison of the bed sizes. Between my MDF machine and the steel one. Not that much smaller, really.

Here is the insert installed in the machine.

Hope to have more updates soon!

Brian Oltrogge
Grünblau Design Studio
Jun 25, 2012, 08:45 AM
Registered User
michaelghammer's Avatar
Wauw!!! Very impressive and good looking machine. A lot of thinking went into that one...

I like your base too.

Keep up the good work.

- Michael Hammer
Jun 25, 2012, 11:32 AM
Team of ONE....or...Team Me
DeadTom's Avatar
That is quite beautiful and impressive, looks like it was done by a big manufacturing company.
Keep up the great work and keep the pictures rolling in.
Jul 04, 2012, 11:11 AM
Registered User
Originally Posted by michaelghammer
Wauw!!! Very impressive and good looking machine. A lot of thinking went into that one...

I like your base too.

Keep up the good work.
Thank you very much for the comments!

Originally Posted by DeadTom
That is quite beautiful and impressive, looks like it was done by a big manufacturing company.
Keep up the great work and keep the pictures rolling in.
Thank you very much, I wanted it to look professional. I hope to be able to sit back and document everything in August and talk to vendors etc... until then, I am only focused on getting it as complete as possible by the end of the month.


I sent the RFQ off this week for the aluminum pieces I also included a clamp for my Bosch router. I hope I will be able to get them before Makerfaire at the end of July.

I am doing a couple of other things while I wait for the aluminum. I finished the base. It is nice to have another work surface...

Then I started making the Platform logo... Kind of a old school frigidaire style script..

I almost sent this out for rapid prototyping and then I remembered that I could use a 60 degree v groove cutter... so I cut this on the MDF CNC. I first milled a curved surface with a 3/8” ball nose then the v groove bit.

After pocketing with an 1/8 bit and a quick coat of poly urethane, I poured some rubber in to make a mold for casting plastic... Here you can get an idea of scale...

Here is the final result... I think it turned out pretty good, I still need to paint it...

Awhile back I tried my hand at making my own cable carrier... I laser cut these out of 1/8" acrylic and glued them together with acrylic solvent...

Seems to work fine, but a lot of work.. so I decided to get a legit carrier that I could fit the cords through. After a lot of looking, I settled on this one.

Mcmaster catalogue

Here is a comparison of the carriers. I might redesign the DIY one at some point, now that I know I could make the bend at a much smaller radius. The major requirement was to fit the DB9 connectors through it.

I expected it to lay flat... Engineered to support the weight of cables?

Finally committed to lead screw length... Here you can see how I am putting a bit of tension on the lead screws.

I had to wait to cut them off in order to see the exact size of the new couplers I ordered.

I am sure the spring version would be fine, I just wanted something a bit more direct since I plan on throwing some weight around and misalignment is not a concern. Yet another thing to add to the R&D pile...

Hope to have more updates soon!

Brian Oltrogge
Grünblau Design Studio
Last edited by Grunblau; Jul 04, 2012 at 11:17 AM.
Jul 05, 2012, 08:01 PM
low tech high tech
vtdiy's Avatar
What happened to the photos on your original thread?

EDIT: Nevermind. Large format pix weren't visible at first, took forever to load, but finally showed up after I'd left the page open in the browser and had dinner.

OP Suggestion:

For internet forum use, photos don't need to be larger than 800 pixels wide. Anything larger is wasted because it is resized to fit most screens anyway. If you fill a post with links to multi megabyte images, and a user with less than high speed connection tries to view it, artwork will appear missing. If the images eventually do load, they won't look any better than if you'd shrunk them down to 100-200 kbytes in the first place. And the page would have loaded nearly instantly if you had.

There are a lot of people in the world without high speed access.
Last edited by vtdiy; Jul 05, 2012 at 11:11 PM.
Jul 06, 2012, 09:37 AM
Registered User
Originally Posted by vtdiy

For internet forum use, photos don't need to be larger than 800 pixels
Before I upload the images, I always resize to 800 pixels wide. I feel that that is the best balance between viewable images and load speed. If anyone wanted bigger images, they would just need to shoot me an email. Likely the original thread was a combination of resized images as I included a lot of pictures that I had uploaded for other purposes. Maybe I'll try 768 px wide in the future as it seems like photobucket resizes the vertical format pictures to this anyway.
Thank you for the suggestion...

Jul 06, 2012, 09:50 AM
low tech high tech
vtdiy's Avatar
Hello Grunblau.

The problem also seems to be that you're linking, rather uploading images to RCGroups. When you link, all pix must load full size, and then re-size to fit the forum column and/or browser. With the large number of photos you are posting, the load time is significant

When you upload to RCG (rather than link), the normal thumbnails appear and the page loads instantly. An occasional link for emphasis is nice, and loads in reasonable time. But a large number of photo links is difficult to render on less than high speed connections.

Hope this helps!

Your work is really nice, by the way.
Jul 15, 2012, 10:45 PM
Registered User
A weeks worth of updates in one post!

I broke down the machine Sunday night to ready the parts for coating....

Here are all the misc fasteners etc... doesn't look like a whole lot. I wanted to catalog everything while I disassembled so I know how many nuts and bolts I ended up using.

Here are all of the pieces... Not all of them will be orange, the parts that will live under the table will be black.

On Monday I got the quote back from the aluminum place..

Turns out after sitting on my files for over a week, a big client takes precedence and I wouldn't get the parts until August. This is understandable, and under different circumstances, I could just wait.

Then came the cost. He seems to think that it would take a machinist 4 hours for the 2D uprights @ $80/hour + material costs!

So I will be checking in with a couple other places. I might have to end up using the machine to mill its own uprights! Grunblau tradition

If I was to make this into a kit, I would likely want to shop it out though.

Late on Friday, I picked up the pieces!!

These first three pictures were taken with my IPhone, and they don't do the color justice. I used my GF's SLR camera for the other photos...

Here are the pieces as they sat on on Saturday morning... I painted the black pieces with flat BBQ paint and tool blacked the edges that were masked off from the powder coating.

Here is a close-up showing the painted logo as well...

Beginning of the assembly...

I finished rebuilding the Platform CNC around 3 PM today. I still have a lot to do, but I feel like I am a bit out of the woods since it is operable again. You can see the insert in the background. I kind of like being able to see all of the metal bits for now so I might leave it out for a while longer.

Here you can see CNCzone's Ger21's Mach3 interface. The giant tool path preview window alone is worth the cost of admission...

I have executed the contingency plan. I sent the aluminum out for a waterjet cutting quote, if it can't get done in time I will have to use the thin steel ones. Still have to figure out the spindle clamp...

Rear view, I still have to attach the cable carrier...

Here is a detail of the leg...

View of the rear of the machine. I haven't been able to step back and have this view because of how close it was to the wall.

That's it for now!

Brian Oltrogge
Grünblau Design Studio
Jul 16, 2012, 01:31 AM
Build to Fly? FLY to BUILD!
Legot's Avatar
This....this is possibly the most beautiful thing I've seen in a long time
I'm weeping...

Honestly, this is a fantastic looking machine. Absolutely fantastic.
Jul 23, 2012, 12:34 AM
Registered User
Originally Posted by Legot
This....this is possibly the most beautiful thing I've seen in a long time
I'm weeping...

Honestly, this is a fantastic looking machine. Absolutely fantastic.
Thank you very much for the comment!

Not a whole lot of progress for most of this week. A friend contacted me about doing some 3D modeling and milling a logo for some of his custom concrete planters. Since I was hoping to pick up the aluminum on Friday, I spent Tuesday, Wednesday and Thursday working on his logo and milling a few molds on the MDF3790.

Here are his signs...

This job was able to pay for the aluminum and cutting. Cool how life works out sometimes... At this point, my MDF machine has paid for itself 10 times over.

I picked up the aluminum over lunch on Friday. I had asked them to make sure it doesn't have any major blemishes... I guess this roughly translates to "Please hit everything with a tigerwheel."

Nothing about an hour with a random orbital with some 220 grit couldn't fix...
You can also see my quick redo on the router clamps. One for my Bosch and one for a 80MM body spindle (future, hopefully)

Closeup view of aluminum...

I also sent out some geometry to be cut out of black vinyl. Couple warning signs and the icons for the machine : )

After tapping about 50 holes this weekend, here is everything installed. It is impossible to take decent photos with the lighting in this room so I'll try to take a couple pics tomorrow.

I am currently drawing mazes and stuff for the machine to draw at Makerfaire.... Getting closer!

That's it for now!


Brian Oltrogge
Grünblau Design Studio
Jul 23, 2012, 06:22 AM
Life begins at transition
Awesome work, just mind-blowingly clean.

your photos almost look like 3D renderings rather than photos!
Jul 26, 2012, 04:15 PM
Registered User
One of the most fantastic things I have..........ever........seen. Wow!
......and thats just the logo No words do justice to what I think of the rest of it.

Oh how jealous I am....still, thanks so much for posting this.

Couple of questions if you'd be willing, hope not to offend.

Did you meet your 3500$ goal?

Are there any pics anywhere of how you rotated the x- nut rather than the screw on your mdf machine?

And.. I'd sure love to know where did you acquire that rubber you used for the logo mold!

Kudos on such an outstanding job! Thanks again for sharing.
Jul 31, 2012, 11:02 PM
Registered User

Maker Faire Pics and Video!

Maker Faire Detroit 2012 was a blast! I even met a few CNCZoners! Couple fun things to note is that more than a few people thought I was with a professional company and we were just showcasing the machine. They were surprised to learn that I was a local and had assembled the machine in my den over the last few months Another comment was people thinking it was a large format plotter, luckily Shopbot was nearby so I could explain that it could do everything they were demonstrating. You can hear them cutting in the background of one of the videos...

Here is a great photo of the CNC at Makerfaire featured at Metromix

Photo Credit: John Froelich

One of the first things you have to do at Maker Faire is to fill out your name tag...

Plotting name on card on my DIY CNC at Makerfaire Detroit (0 min 37 sec)

Solving a mazes with the Playstation controller...

Maker Faire 2012 Drawing (0 min 22 sec)

Among other things I printed one of Daniela Hellmich's designs for a wooden marquetry medallion to show that it can do some intricate shapes not just simple mazes...

We had a great time and even took home an Editor's Choice Award to top it off!!!

Now I just have to find a permanent place for it and finally install those limit switches!

That's it for now, I hope to have some actual cutting videos soon!


Brian Oltrogge
Grünblau Design Studio
Last edited by Grunblau; Jul 31, 2012 at 11:09 PM.
Jul 31, 2012, 11:26 PM
Registered User
Originally Posted by billcat
One of the most fantastic things I have..........ever........seen. Wow!

Couple of questions...

Did you meet your 3500$ goal?

Are there any pics anywhere of how you rotated the x- nut rather than the screw on your mdf machine?

And.. I'd sure love to know where did you acquire that rubber you used for the logo mold!

Kudos on such an outstanding job! Thanks again for sharing.
Thank you for your comments! I hope to know the final pricing in the next month or so... I began with that as my target, but then began shooting for making a much better machine than the Rockler one.... The have a new machine for $4k that is a somewhat closer comparison, we will see!

These renders are directly from the plan set for my MDF machine, the MDF3790..

Assembled view...

Exploded view...

Belt tensioner assembly...

If you would like any more info on this build it can be found here

Here are the links to the Smooth-on stuff...


Both are a part A and B by volume... you mix up the 2 parts and pour. The rubber takes over night and the plastic takes about 10 minutes. It starts out clear and then turns white as it cures.

Here is the process from Smooth-on...

How to Make a 1-Piece Block Mold with ReoFlex Urethane Rubber (3 min 17 sec)

Hope this helps!!


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