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Joined: Mon Feb 06, 2012 3:04 pm
Posts: 258
Real Name: Alex Crane
The 213V are an excellent drive. Pretty much they are the same drive I use (the 203V's) with an added step multiplier selection. As far as your 950 OZ motors, those should be MORE then enough. In all honesty, those would be the size I would choose for a full bridgeport retro-fit. Running a benchtop with those will be cake. I think you are set up very nicely. I like to stay at least 40% above max torque at max speed as a safety net. I think you are easily there.

Here is the info for my machine guys:

Universal Machine Inc
615 East 44th Street
Garden City, ID 83714
(208) 375-1110

I highly recommend them. They did a ton of machine work on my CNC and did really good work. They will also help you design parts that are easily machines and cost effective. It's a two guy shop, Craig and Terry run it.

Alex


Thu Oct 11, 2012 10:05 am
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Joined: Wed Mar 07, 2012 10:40 am
Posts: 123
Real Name: Robert
OK, that's good to know--I had no experience to decide what torque was needed under load. By the way, my mill is a knee mill, not a bench top--and I will drive the Z quill, not the Z table. The torque requirement is very high with a big lever handle to raise the table.

Bob


Thu Oct 11, 2012 10:15 am
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Joined: Mon Feb 06, 2012 3:04 pm
Posts: 258
Real Name: Alex Crane
Bob,

I just talked to a friend today about his mill conversion. He modified a Jet benchtop mill, and is having pretty good luck with it. He is not using ballscrews either, just the ACME that the table is already equipped with. He is not using steppers nearly the size that you have selected, and has yet to run into any power problems.

He DID say that 1:1 was no good when he first tried it. The resolution just was not good enough. He even tried 1.5:1 and decided he needed to finally go to 2:1 which seems to be working pretty well for him. He is also using an open loop (no feedback) system, and it has worked well for him so far with no issues.

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Thu Oct 11, 2012 12:51 pm
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Joined: Wed Mar 07, 2012 10:40 am
Posts: 123
Real Name: Robert
Hi Alex,
Oh, I didnt think of that. The steppers do 1.8 degree steps, and the mill does .125 inch linear per turn, which would translate to 0.000625 inch per step, about half a thousandth. But the backlash is 4 thousandths--so I suspect my problem will not be direct drive, even if I just do full step rather than half step or better. That adds up to about 8 steps. I wonder if the Jet mill has a faster screw pitch as the reason why his accuracy was bad at 1:1. Or maybe I'm not figuring this right? I'll double check the 1/8" per turn when I get home but I'm pretty sure that's what the DRO reported.

Bob


Thu Oct 11, 2012 1:24 pm
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Joined: Mon Feb 06, 2012 3:04 pm
Posts: 258
Real Name: Alex Crane
I didn't get much about reasoning for this when I talked to him. I agree, the math seems to be fine. Just passing along what he said. Without any gear modification your Solsylva is a direct drive with 5 turns per inch, and resolution is no where near a problem. Yes, it's not a knee mill, but still the resolution is pretty high. I am kinda with you on the direct drive after giving it a second thought. Hrm...something to be thinking about anyways. Perhaps it was not resolution her was referring to, but gear reduction for power. In that case your well over twice the holding torque he is running. I would throw it together and see what happens. Good news is, it seems the ACME screws work just fine in these.


Thu Oct 11, 2012 11:06 pm
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Joined: Wed Mar 07, 2012 10:40 am
Posts: 123
Real Name: Robert
Well, the mill CNC retrofit is going well so far, Y bracket made, doesn't look too ugly (I'm no machinist), motor mount done. I did the Y axis first as a proof of concept because X will require cutting off the leadscrew end and Z will be harder. I want to make sure the concept works before committing the mill to a point of no return. Antek power supply and motors and drivers and heatsinks and couplings all are here, going in a nice panel from the reuseum. I'm designing a panel for Mach3 using the Ultimarc switches.

I'm approaching the point where I need to get software. Looks like industry standard is Vcarve Pro and VisualMill. That's $1900. Any smarter/cheaper options for a windows machine? I also will have to get Mach3. Itried f-engrave but I've been spoiled by vcarve...

Bob


Tue Nov 06, 2012 4:29 pm
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Joined: Wed Mar 07, 2012 10:40 am
Posts: 123
Real Name: Robert
Yow. One place to run from is bobcad. High pressure buy-it-now sales tactics, on the spot cost reduction if you buy it now only, you have 30 days to make sure it works (after you buy it) if it doesnt, we'll give you your money back... right. Maybe I'm reading them wrong, but I really didn't like my experience dealing with them. I got out of there as quick as I could.

I'm thinking even though VCarve/Mach3 isn't really mill 3D CAD/CAM, it will do what I need to control the 3 axis setup I have. Thoughts? VisualMill turns out to be a plugin, you also have to buy something like solidworks and autocad--many $thousands. The reason I looked at Bobcad is they are the only cheap total solution--but some reviews are pretty negative on the reliability of the SW, and some have complained about constant upsell, and my own experience on the phone says red flag all over it.

If I have Mach3, all I need is a GCode list. Most brackets and panels could be designed with VCarve, and if I had to, I could write my own GCode file generator for really abnormal shapes. But 3D CAD would be cool--all you 3D printer types, what do you do? Is additive CAD (3D print) substantially different than subtractive (mill, router)? I really don't see any workable free/open source subtractive CAD/CAM out there. Did I miss something obvious?

Bob


Fri Nov 09, 2012 9:56 am
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Joined: Wed Jun 06, 2012 9:30 pm
Posts: 334
Real Name: Randy
Skeinforge has a carve type function to run mills. I have not tried it that way yet, but I expect it would be similar to tuning a printer. You start off with parameters that would be within tolerance for you machine and then run tests until you get it dialed in just right.

Now a mill does not have flow rate of different plastics to worry about, but the feed rates and layer height would have to be tuned just right.

If I recall you have a functional CNC router, we could try some codes for it and maybe process a simple shape to see if it is able to.

What is the total height on the CNC router? When I had access to a CNC router I was able to have it shape a little half sphere using really basic tool path software. That was before I was introduced to skeinforge.

Let's talk there may be an opensource way, but it may not be everything you want / need.

Randy


Fri Nov 09, 2012 10:07 pm
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Joined: Wed Mar 07, 2012 10:40 am
Posts: 123
Real Name: Robert
I'm back! I finished my work project and left for a long anniversary trip. And jumped right back into my projects. The milling machine conversion is the biggest effort, and slow going since I'm more of a hacker than a machinist. But so far, that's been going well. A couple of pics below.

Am I OK posting this stuff? I'm not not one of the sharper pencils in the lot when it comes to people skills--but I don't see other projects posted here (other than the massive mustang project!) and wondering if I'm missing something...

I'm also starting work on the FPGA seminar, are people still up for that. I like the $99 board somebody posted, that's got a very good part on it. I'm thinking of showing you how to make a customizable logic probe/analyzer out of that--might be handy for troubleshooting skipped steps on your 3D printers or other glitches.

Bob


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Thu Dec 27, 2012 10:26 am
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Joined: Mon Dec 12, 2011 12:26 pm
Posts: 319
Real Name: Sol
You are absolutely ok with posting this stuff up - that is what this forum is for! The rest of us are too busy hacking to post about it.. ;)

I'm very interested in the FPGA primer too - will be good to pick up more knowledge.


Thu Dec 27, 2012 12:22 pm
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