Hafco (RF-47) CNC mill and lathe conversions - finished

I wanted to share the recently completed CNC conversion of a Hafco HM-47 mill and AL-336D lathe, with the hope to inspire others to do the same and provide some encouragement for those working late into the night on their own projects.

The basic specs of the pre-converted machines can be found at these links:
Mill: https://www.machineryhouse.com.au/M125D
Lathe: https://www.machineryhouse.com.au/Centre-Lathes

A summary of the major components in the build as follows:
Mill:
- DMM-Tech servo, Dyn2, 750W servo motors on X, Y, Z axes
- Noulei C5 grade rolled double nut ballscrews on all axes
- Marathon Electric 2.5HP spindle motor
- Teco L510 VFD
- Mesa 7i76e controller
- LinuxCNC
- Z-axis brake (activated when power is shutdown)
- Festo air management
- One shot oiler
- Custom user panel

Lathe:
- DMM-Tech servo, Dyn2 servo motors, 400W on X axis, 750W on Z axis
- Noulei C5 grade rolled double nut ballscrews on all axes
- Marathon Electric 2.0HP spindle motor
- Teco L510 VFD
- Mesa 7i76e controller
- LinuxCNC
- Festo air management
- Spindle speed encoder
- Custom user panel

The accuracy achieved on the mill is less than +/- 20 um for X and Y axes and +/- 25 for Z.
The lathe achieves around +/- 20 um on both axes.

http://www.cnczone.com/forums/attach...d=383786&stc=1http://www.cnczone.com/forums/attach...d=383788&stc=1http://www.cnczone.com/forums/attach...d=383790&stc=1http://www.cnczone.com/forums/attach...d=383800&stc=1
http://www.cnczone.com/forums/attach...d=383792&stc=1http://www.cnczone.com/forums/attach...d=383794&stc=1http://www.cnczone.com/forums/attach...d=383796&stc=1http://www.cnczone.com/forums/attach...d=383798&stc=1

Excellent Work!

Is Linux CNC not compatible with the DMM break out board? I just had a 3 axis package quoted through them and would prefer to be running on linux when done.

I believe the DMM board is compatible with LinuxCNC, but best to confirm with them. I found them to provide excellent customer service. I wanted an Ethernet connection and some of the other functionality that the Mesa 7i76e controllers provided.

Looks great. Did you convert them to make a particular product?

Thanks! Yes, I'm building custom electric bikes. Majority of turned parts are either 4140 CrMo or 1020 mild steel. Majority of milled parts are 6061 but some 4140 too.

Quote:

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Originally Posted by IIOIOII

Thanks! Yes, I'm building custom electric bikes. Majority of turned parts are either 4140 CrMo or 1020 mild steel. Majority of milled parts are 6061 but some 4140 too.

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Bicycles or motercycles?

Bicycles, pedal with electric assist

Quote:

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Originally Posted by IIOIOII

Bicycles, pedal with electric assist

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Pics?
I have a Tangent Ascent on a Giant Team
And a BBSHD on a Specialized with a Lefty.
Are you incorporating a torque sensing bottom bracket?


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The ebikes we're building are entirely custom; frame, fork, saddle, etc. We have trailed a BBSHD and liked it, however have decided to use a Crystalite 2000W rear hub due to styling and packaging reasons. We're not yet ready to release pictures of the bike in full, however one attached of the various turned parts made on these machines. Also, you can follow the build if you search for Brian Tanti's Workshop on Facebook.

Re. the bottom bracket, yes, using a torque sensing BB. Likely TDCM which has worked well in our development testing.

Quote:

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Originally Posted by IIOIOII

Re. the bottom bracket, yes, using a torque sensing BB. Likely TDCM which has worked well in our development testing.

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I would love to use one on my Tangent. I just cant find a Torque sensing BB in my width. It is on a Team Downhill. I have thought of buying somebody else’s and fitting it to a new spindle!


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Thinking about your BB width problem, it wouldn't be too hard to turn up a new axle for the crank. I've taken apart the TDCM and the setup is fairly simple. Changing the length of the crank axle will of course change the torque sensed, but if you're using Cycle Analyst, you can compensate for this.

Quote:

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Originally Posted by IIOIOII

Thinking about your BB width problem, it wouldn't be too hard to turn up a new axle for the crank. I've taken apart the TDCM and the setup is fairly simple. Changing the length of the crank axle will of course change the torque sensed, but if you're using Cycle Analyst, you can compensate for this.

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Thanks for that response. I had wondered that same thing, if I could adapt the sensors to a different BB shaft.
You didnt take pictures of 1 apart did you?


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Very nice! I am attempting the same thing with my HM-46 in Brisbane.

I have been busy scraping the dovetails in a disassembled state, they were really out of whack and the mill is almost new. The saddle actually rocks on the surface plate and is curved like a chip - out by several thou. Somehow when together it wasn't quite as inaccurate.

How is the for/aft lean of the column? I modelled a similar column in Inventor FEA quickly and got 0.02mm of movement at the top under the moment caused by the head being on the machine. I heard that this is their weak point (thin column, heavy head). I hope to alleviate it with gas struts or a counter weight in a fashion similar to this - https://www.cnczone.com/forums/bench...d-support.html

I bought Chinese servos instead of DMM - I fear I might regret this, but the price difference was 100%. Still, should be ok for a 'toy' mill, no plans for serious production... yet.

Looks like you've done a great job!

Do you mind sharing details of how you mounted and connected the motor to the Z screw? I'd like to do that to mine to make the head easier to move up and down. Do you find it a problem with no counterweight?

Regards, David.

Thanks!

The Z-axis was directly coupled by a zero backlash 'spider' coupler. If you look closely at the first image at the start of this thread, you'll see an aluminium plate. I machined this to suit the ball screw bearing support and bolted it to the top of the Z-axis casting. Above this I fastened a 3D printed motor support. To add some additional strength to the motor support, I used some thin wall steel tubes to act as crush tubes for each of the fasteners.

The DMM servo motors I used (750W) with the pitch of the ball screw were well overrated and could easily lift the weight of the head. To avoid the head falling under its own weight when the power was turned off, I added an electromagnetic brake to the bottom of the Z-axis ball screw, which was normally on (brake applied) when the power was off. This worked well.

The only problem I had with the Z-axis was not related to the motors or ball screws, but rather the overall rigidity of the casting when machining heavier materials (i.e. 4140 CrMo). If I took too heavy a cut, the Z-axis would flex and subsequently result in a poor surface finish and lower tool life.

@j3dprints: Apologies for the slow reply on this...

I found I had to tweak the saddle on the mill too. Wasn't miles out, but enough to warrant some attention.
Although I didn't measure it, I'm sure there was some movement in the column/head assembly, likely greater than 0.02mm. I didn't use a counterweight and I'm not sure whether it would have really made much of a difference due to the flex incurred whilst machining (refer previous post).

How are the Chinese servos going?

Just out of interest, what settings did you use for the dyn2 drivers. I managed to get the mill moving the correct amount but clearly I need to do some tuning of the parameters.

Also, not sure if you set acceleration and velocity in linuxcnc but if you do could I bother you for those settings also?

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It's just a hazy memory now unfortunately and I've also sold the machines, so can't check for you either sorry.
This DMM video https://www.youtube.com/watch?v=UvBxhX5xNeg should help steer you in the right direction.

IIOIOII,

where did you obtain the collapsible covers for the leadscrew on the lathe? I tried googling looking for that but I get every and any result that has nothing to do with it! Ughhh. Perhaps I just don't know how to word the query.
Thanks.