Neil Rosenberg published a new build:

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Thanks Mark. I placed a large order with OpenBuilds today. Only thing in short supply was the eccentrics, hopefully more on the way...

TTYL!

Neil, I too am working on a OX direved design. Need to figure out a few more things before I order parts. I do have a question and a concern about your built.

Would love to know what exactly you are doing for the z-axis rack, where are you getting it?

And the concernt I have. I think your machine is going to rock and roll, there is going to be alot of stress on those pieces of 2080 that act as the stand for your machine. They are going to cause alot of flexing back and forth the way it is built. I have not had a chance to look at the solidworks files yet, do you have some sort of beams running between them, like the Routy has?

Hi there Nick, thanks for the follow-up.

The z-axis rack and spur gear are from SDP-SI.com, part numbers S1811Y-RC-1 and S1086Z-024S016, cost at single unit qyt is $57.44 and $18.57 respectively. They are both in stock. The spur gear is .25 bore, good for the NEMA 23 motors I chose.

Also there are three full-length 20x40 vbeams running the long direction, mounted with angle brackets for stability. Here's a screen-shot of the underside (brackets are not yet shown in the model):

Oh another comment -- the "spoiler board" is going to become a vacuum table. There's a neat video on YouTube by Sean Martin of DonekTools:



I don't think the vacuum table needs to be as thick as what he did -- there's really not much airflow, in fact almost NONE during operation, otherwise it won't draw down the parts. Mine will probably be about 1/2 as thick as his. I like his idea of putting a sacrificial layer on top, but I'd probably screw it down rather than glue it.

Also, at about timestamp 6:58 there's great footage of (I assume) his kids helping him build a CNC Mogul CNC router. I almost bought one of those, but there was just too little information on the web page (http://cncmogul.com/) and besides, I really wanted to roll my own

The CNC Mogul appears dead. No one on CNCZone has recieved any info from them. And I even sent a few emails and got no response. Sad.

As far as your build. Those ribs should be the same size as the 2080 on the ends. Or mount 2 of them at the bottom and the center one at the top to support the top surface. This would give you a much stiffer machine.

Hey, how 'bout sandwiching in the middle 20 x 20 between to MDF sheets, only first cross route some dado channels to channel the air through? Then the 20 x 20 becomes the ribbing for the vacuum table.

I've also read somewhere the shop vac does better, last longer, if you let some air always leak through. i.e. building in a little air leak valve at the far end of the table from the vacuum pickup.

The Sean Martin, Donek video is great! I LOL when the kids were assembling the CNC Mogul.

Sandwhiching the channel could work, but sealing the ends would be a PITA.

I'm playing with different ideas on the construction of the vacuum table, thanks for the suggestions. It may work to have the vacuum box provide most of the long-direction racking stiffness of the machine. Perhaps I'll remove the three lengthwise 20-40's, nestle the box in the open space, and attach to the end rails high and low. Just need to avoid the motors...

As far as the vacuum itself, that's a good thought to add a "leak" hole at the end away from the hose (I may make it adjustable somehow) -- don't want to burn out too many shop vacs

Updated model available, now has a start at some of the ideas above.

Neil,
Nice work.. I really like the vacuum table feature. Any chance of getting your plates as .STEP (or DWG) files for guys without SolidWorks?

Or anybody else have experience with good way to convert SLD to IGES / STEP?

I can provide any format that SolidWorks can export.

I have a few more days of detailing, then I'll post them. Let me know your preferred format please. They will probably import as uneditable but you'll be able to get all the dimensions and details.

Also FYI there's a free SolidWorks eDrawings Viewer that may allow you to view the models I've already posted. Here's the link: http://www.edrawingsviewer.com/ed/edrawings-viewer.htm

Neil

Similar to how Sean Martin (Donek) did it -- drill the current (shown) permanent top with a matrix of holes, attach a sacrificial spoiler of MDF on top, glue and use vacuum as a hold-down. Once dry, re-drill the same set of holes, but this time through the MDF. Then surface skim the MDF in place to true it to the machine.

The MDF spoiler can be skim machined as needed. When it gets really thin I'll replace it, re-drill and re-flatten to get started anew.

I don't like the idea of gluing the sacrifice sheet down. It will be a pain to replace it. A few screws on the perimeter will be much better.

Good thought, thanks.

I have the eDrawings 2014 from Solidworks .. how do i get the dimensions out of the pictures ?? How do i display dimensions of say Gantry Slide Mount B. SLDPRT or the Side Plate<1>, Right SLDASM (read-Only) from the frog ?? i can isolate just the plate but haven't figured out how to get the Dimensions via the eDrawings 2014 software.

I am now building the Frog, going well so far. I plan to post some photos soon.

BTW I have just posted an updated version (1.3), now includes provisions for a belt tensioner for the dual-motor X axis, plus holes in the end plates to allow the belt to "escape". Makes life a lot easier. I'll put up photos of that as well.

As regards John89702's question, I've been trying to enable measurement in SolidWorks, but no matter what I do eDrawings doesn't seem to see it. I was however able to import the .sldprt files into Inventor 2013 and measure from there. Perhaps other packages can do the same?

I will be happy to export any of the parts files in whatever format you need (iges, dxf, stl, etc.) -- just say the word.

I have the program eDrawings and all I can do with it is use it as a viewer, and I think that's all it is intended to be but I can be wrong about it. If the dimensions are not on the drawings themselves, I can't 'measure' them. To do that you need a program that can manipulate files which I can't do in eDrawings.

Apparently I need to have SolidWorks Pro to enable measuring, sorry. I have the Standard version.

In the meanwhile, my offer stands. If there's a request for an export of one or more parts, I'll be happy to provide.

Without knowing much, purchased Turbocad Pro V19 it might be able to see .dxf ... google sketchup is free and then there's adobe's .PDF SolidWorks viewer doesn't do much for me.

Thanks Mark

It's coming together pretty fast now. I've already checked the electronics, time will tell if this $58 4-axis Chinese/Ebay driver board will be a boon or a headache. Seems ok for now, but the proof is in the cutting. I already fixed a tiny solder blob on it that prevented 2-directional travel on one of the axes. Mach3 is great with it, easy to set up.

BTW I'd like to share a bit of feedback with whomever about a few of the OpenBuilds parts. Nothing earth shattering, but perhaps I can help improve things for others. We can take this offline if you like.

Also I have concerns about the GT2 glass belt for my y-axis. Seems pretty lightweight, I wonder how stretchy it is. Do you have any data? I ordered a Gates polyamide (Kevlar) GT2 belt -- when I get an opportunity I'd like to do a bit of A-B testing vs the glass belt.

Neil

Been looking for the 3mm pitch GT2 belts and pulleys, seem to be pretty rare. Do you have a good source?

Neil
Stock Stock Drive Products has good selection of 3mm pitch GT2 parts.

https://sdp-si.com/eStore/Catalog

Thanks Matt, I'll have a look.

I did my first cutting today, very exciting! Showed me all sorts of things that I need to do better, starting with the right speeds, depths of cut, material stabilizing. I also had to do some revisions in Mach3 to the acceleration ramps and maximum speeds of the various motors to eliminate a bit of jerky motion. I'm running 1/8 microstep on x and y, 1/16 on z. On paper this gives the system .001" granularity or better, but I'll be happy with .01" to .03" accuracy in actual use.

The good news is that the electronics and software performed flawlessly, and after some fussing with the bit mount (kept wanting to loosen up) I was able to get clean repeatable lines. Every indication is that with good bits and proper speeds it will do quite nicely. However, this is no Bridgeport knee mill; the speed and depth of cut can't compare with an industrial strength machine with leadscrews everywhere and massive frame components. No surprise here.

I do have some concerns about the lightweight trim router that I'm using, it's a new Horrible Freight model 44914, cost all of $30. It emitted a fairly strong burn smell, but in truth I did abuse it at the start, even stalled it once. I also had difficulty getting it to tighten on a few of my 1/4" shank bits. Cheap is cheap, I guess. It did work well eventually once I got my bit mount and speed/depth worked out.

Onward!

P.S. I also see that my grab bag of old routing bits will *never* do -- love the smell of burning wood (NOT!). Anyone have a favorite source for routing bits, good deals, etc?

Neil,
I am looking at stepper options and I am curious what is the torque of the motors you are using? You mentioned that you stalled the router.. did you have any missed steps / are you happy so far with the stepper motors you have?

If you can you post the files for your gantry plates as .STP or DXF. That will allow most anyone to Import them into 3rd party software and generate gcode etc.