[ninefinger]

OK,

I've started the process of getting an IH clone mill and sourcing all of the necessary bits to convert it to CNC. Attached is my spreadsheet that I've put together for me to keep track of what I'm doing and how much its going to cost me. I've listed the vairous options for items I looked at and marked those that I've selected.
As the machine is not scheduled to arrive until sometime in January this post is a little bit premature but I'll update it as parts arrive.

Regards,

Mike R.

[MichaelHenry]

Just curious - what is the accuracy and backlash of the ball screw and ballnuts?

Mike

[ninefinger]

Just curious - what is the accuracy and backlash of the ball screw and ballnuts?

Mike

Mike,

From the specs published for the 3 ball screw vendors I've listed the accuracy is +/- .003"/ft for the Rockford ball screws, .0018"/ft for those from homeshopcnc and the Roton are not published that I could find but I've read they are +/- .010"/ft.

The ball nuts by Rockford are listed as 0.005" backlash max, I plan to use 2 and preload them to remove any backlash.

I hope this helps,

Mike

[BobWarfield]

Mike, I liked your spreadsheet. It should be helpful to anyone that wants to start one of these projects.

Best,

BW

[SCzEngrgGroup]

Mike,

From the specs published for the 3 ball screw vendors I've listed the accuracy is +/- .003"/ft for the Rockford ball screws, .0018"/ft for those from homeshopcnc and the Roton are not published that I could find but I've read they are +/- .010"/ft.

The ball nuts by Rockford are listed as 0.005" backlash max, I plan to use 2 and preload them to remove any backlash.

I hope this helps,

Mike

Nook XPR screws are +/-0.001"/foot, for only a little more money than the others. They are also dead-smooth - almost like ground screws.

Regards,
Ray L.

[Hans_G]

sorry to go off topic... Ray, with the Nook XPR's aren't the ballnuts really expensive? I got a quote for SSN series ballnuts in the $300 range and PRN in the $500 range. Is there a cheaper way to complete the assembly?

[SCzEngrgGroup]

sorry to go off topic... Ray, with the Nook XPR's aren't the ballnuts really expensive? I got a quote for SSN series ballnuts in the $300 range and PRN in the $500 range. Is there a cheaper way to complete the assembly?

I don't recall what the ballnut pricing was, but it wasn't unreasonable compared to the others I looked at, and they were certainly better quality. I ended up making my own double nut assemblies, which cost about $150 each, IIRC. I do know the total cost of my three screws (60" x 1", 24" x 1" and 18" x 5/8") plus all 6 nuts was right around $1000.

Regards,
Ray L.

[BobWarfield]

Sounds like maybe $1000'ish versus $700'ish to go Nook?

I think I'd go with Nook if it was my money. Nothing wrong with Rockford, that's what's in my mill. OTOH, I did measure their accuracy with some glass scales and they were just within the 0.003" per foot. It'd be nice to get 3x better given the long travels of these mills.

Cheers,

BW

[MichaelHenry]

Mike,

From the specs published for the 3 ball screw vendors I've listed the accuracy is +/- .003"/ft for the Rockford ball screws, .0018"/ft for those from homeshopcnc and the Roton are not published that I could find but I've read they are +/- .010"/ft.

The ball nuts by Rockford are listed as 0.005" backlash max, I plan to use 2 and preload them to remove any backlash.

I hope this helps,

Mike

Thanks - the backlash I saw in Google searches for similar products caught my attention, but I didn't realize that could be preloaded out.

Good luck on the project.

Mike

[ninefinger]

Well I've added to my spreadsheet a second tab where I did the calculations for ball screws as laid out by Rockford ball screw. Turns out that with the assumptions I've made :withstupi that I can run the 5/8" ball screws for X and Y but the Z axis is best off with a 1" screw, or the higher load rating on the smaller screws.

Also, using their calculations for torque required it looks quite reasonable that 350 oz-in servo motors can be used on X and Y (50 oz-in continuous) but that Z needs a big servo (ie 850 oz-in pk / 170 oz-in continuous), might be able to reduce this requirement by using a smaller screw with the .200" pitch versus the .250" for the 1" screw. I'll work that out another night. Time for me to get to bed...


I'll attach the spreadsheet here again as I can't figure out how to edit my previous post (still a complete newbie on the forum)

Mike R

[SCzEngrgGroup]

You can get 5-pitch 1" screws from homeshopcnc.com, and linearmotionbearings2008 on E-Bay has 1" screws at 10-pitch.

Regards,
Ray L.

[ninefinger]

You can get 5-pitch 1" screws from homeshopcnc.com, and linearmotionbearings2008 on E-Bay has 1" screws at 10-pitch.

Regards,
Ray L.

Thank Ray for the tip on the ebay vendor - looks like it could save me some $$. I have been checking out homeshopcnc.com but they only carry the 16 and 20mm screws (ie 5/8" & 3/4").

Do you have any experience with the REX ball screws and antibacklash nuts? How well do they work compared to a preloaded set of ball nuts?
Is the anti-backlash up to the full dynamic load rating? Sorry for all the questions but I've got time to analyze the crap out of this till my machine shows up so I may as well do it.

Thanks again,

Mike R

[SCzEngrgGroup]

Thank Ray for the tip on the ebay vendor - looks like it could save me some $$. I have been checking out homeshopcnc.com but they only carry the 16 and 20mm screws (ie 5/8" & 3/4").

Do you have any experience with the REX ball screws and antibacklash nuts? How well do they work compared to a preloaded set of ball nuts?
Is the anti-backlash up to the full dynamic load rating? Sorry for all the questions but I've got time to analyze the crap out of this till my machine shows up so I may as well do it.

Thanks again,

Mike R

Mike,

You're right, they are 20mm, not 1", though that should be plenty big enough for your needs. I belive the linearmotionbearings2008 ones I was quoted were 25mm 10 pitch.

I *will* have experience with the Rex screws in a few days - I'm expecting to receive two of them either today or Monday, that will go into the Bridgeport quill drives I'm building. So far, everything I've bought from HomeShopCNC has been very high quality, and their support is great. I've been buying from them for years. They may not be the cheapest, but to me it's worth the difference to deal with someone I can trust, and I know I'll get support.

Regards,
Ray L.

[ninefinger]

Just an update on my progress so far.

Parts ordered and received to date:

Shars Tools: end mill holder set, ER40 collet set and chuck, drill chuck - all NMTB 30 - received in good condition and ~ 10 days after order placed. Thats good for US to Canada orders & shipments.
Whale3 servo drives (qty3 ) and LPT break out board - ordered 2 days after the Shars order and received in 10 days from Poland!
3 encoders, 2 capacitors and some power resitors from Digikey - ordered them at 5:30pm eastern time yesterday and received them at noon today? WOW

Orders placed but not received:
The mill & stand & ISO30 spindle option. Expected in January. Called and ask to have the mill motor upgraded to the factory 2hp 3phase option so I can run a VFD. ($80 CDN)
Econobelt.com (qtcgears.com) - pulleys and belts - 3 sets for 4:1 reduction and an experimental set for 5:1 if needed. ($103)
Ball screws, nuts, bearings and mounting blocks - choice at this time is linearmotionbearings2008 on ebay. Excellent price and feedback from customers I've read here at CNCzone seems to be very positive if something isn't right with the parts when they arrrive (ie seller makes things right)
I keep waffling on the Z axis ball screw size but I believe I'm going to end up with all 3 ballscrews at 3/4" diameter. I figure that reducing the weight the z-axis servo and ballscrew have to move is the best plan as it lets me use the same servos for all 3 axises. I can use a bigger reduction (5:1) on the Z axis if needed to increase the torque available. Trying to decide wether to use gas struts or counter weights. Need more info on gas struts before I decide...

Servo motors. Well I found the "ideal" motor for the Whale3 drives(ie armature resistance = 2ohms & capable of 80v results in higher torque than others) - unfortunately the manufacturer (Glentek) is unresponsive to my emails. Looks like I'll have to compromise and go with slightly smaller servos or use larger servos and a power resistor to bring the armature resistance in line with the drive specs (1.5 Ohm min)

Variable frequency drive: $159 plus $50 shipping for a total of $209 - for a 3hp VFP single phase in 3 phase out. GE brand with documentation avalable online! Anybody out there with experience buying from Dealerselectric.com or with any of these VFD"s? http://dealerselectric.com/item.asp?cID=&PID=1028
I'm a little scared as the price seems too good to be true?

I'll snap a picture or 2 of all the parts so far in a little bit and post them.

Cheers :cheers:

Mike

[BobWarfield]

Smokin' deal on the VFD. No idea how good it is. Get the doc and give it a good going over.

Here's the one I purchased:

http://www.driveswarehouse.com/Drive...0-022NFU1.html

Similar unit. There are a number of folks on CNCZone that have made this one work.

Best,

BW

[Dirty Engineer]

Wow I'm going to follow this thread closely as this is the identical setup I would like to go with. Thanks for the awesome documentation so far! If you don't mind me asking what part of Canada are you from?

[ninefinger]

Wow I'm going to follow this thread closely as this is the identical setup I would like to go with. Thanks for the awesome documentation so far! If you don't mind me asking what part of Canada are you from?

I'm in Ottawa. Kinda sucks trying to find surplus, tooling, materials and other electrical or mechanical tidbits here to do experimenting/inventing as the majority of surplus is used office chairs and desks. I guess thats what I get for living in a government town...:violin:

Mike

[ninefinger]

I got into the shop tonight to see just what I have so far and it looks like its starting to come together!

I dug around and found a couple of things I thought I'd need to buy, like 3 relays, an LPT to Centronics cable and a bunch of ethernet cables. Plus I found some salvaged optical switches that I'll need to test but I can probably use as limit / home switches.

So I laid it all out on the floor and took a picture.

I also have a small pump (1 GPM / 3.8 L/min) that I'll use for coolant, if its not big enough I'll upgrade later. Also a solenoid actuated valve (future air operated ATC or air-mist coolant?) and a stainless reservoir..

Only a few items left to order (the expensive ones!)- VFD, servo motors, ball screws and nuts and bearings.

PS if anybody knows where to find 450 Oz-in servo motors I'd appreciate it. Seems that this size is hard to find - but likely has the right armature resistance for the Whale3 servo drive (i.e. greater than 1.5 ohms but not by much)

Mike

[ledinc]

Are there any differences between the Clone machine and the machine from IH in terms of parts, or the quality of parts? I'm thinking of buying a mill and liked the IH because of the larger cross travel. May convert it later.

[Starleper1]

I got into the shop tonight to see just what I have so far and it looks like its starting to come together!

I dug around and found a couple of things I thought I'd need to buy, like 3 relays, an LPT to Centronics cable and a bunch of ethernet cables. Plus I found some salvaged optical switches that I'll need to test but I can probably use as limit / home switches.

So I laid it all out on the floor and took a picture.

I also have a small pump (1 GPM / 3.8 L/min) that I'll use for coolant, if its not big enough I'll upgrade later. Also a solenoid actuated valve (future air operated ATC or air-mist coolant?) and a stainless reservoir..

Only a few items left to order (the expensive ones!)- VFD, servo motors, ball screws and nuts and bearings.

PS if anybody knows where to find 450 Oz-in servo motors I'd appreciate it. Seems that this size is hard to find - but likely has the right armature resistance for the Whale3 servo drive (i.e. greater than 1.5 ohms but not by much)

Mike

Ajax has a 29in/lbs servo which is 464oz/in. They are pricey though at $715