HM35 Gear Head Mill CNC Conversion

[Kipper]

I use 2.5MM pitch screws on mine although if I was to replace I would go with 5MM as the 2.5MM with 2:1 resolution is no longer needed as no more machine dies for an injection moulders is needed (they bought a VMC) I use 1.8nm motors at the moment and have no need for any more "power" they are Chinese Nema23 FL56 type. After 8 hours of machining today they were (the motors) 36C and the gearbox output shaft 32C (Cooled by the coolant which was 33C) Todays CNC project was a flying gantry router upright. Drawn and programmed in Bobcad V21 and processed by Mach3

YouTube - Bobcad21 Animation

YouTube - Bobcad21 Animation

Both programs I like very much Images of my mill internals can be seen on my gallery site

[XaserTech]

Originally Posted by dmenz Hi Adam and Kipper, I agree with Adam on the quality of Kipper's enclosed mounts - great work. Adam good point about having the mounts covered as I guess swarf and coolant would become an issue in the end. Sounds from you both that ballscrews will be essential eventually for long life and high accuracy so I will head this way. What ball screw pitch and diameter do you gents suggest based on your experiences? Also what sort of machining were you doing Kipper to wear out your ACME screws and nuts as I will be machining mild steel mainly? What motors do you guys use as in brands, torque and achieveable RPM and what drives? I have used Ability Systems G Code controller previously for a 4 axis 3D profiler but unfortunately it only supported 2 axis G02 and G03 commands so I had to code 3 axis moves directly into the Indexer engine. However it does support using multiple parallel ports very well. I have an unused, so far, copy of Mach3 which looks promising. I have also started looking at EMC^2 for its multi port capability but on Linux which may have better timing control than Windows. Multi ports and therefore more axes will be useful for multi axes machines and even Robot arms or just for more inputs like Ability Do you guys have any comments or suggestions on software? Hopefully at the end of this project I will know a lot more and have a light duty for steel but useful 3 axis CNC mill and drill of course. Regards dmenz

Hi Doug,

Well currently the ACME screws are I think 25 or 30mm diameter with 3mm pitch I would think you could quite safely get away with a 20mm dia ball screw. 5mm pitch would be ok because if you use stepper motors you’ll probably need to gear down which will in turn increase the resolution of the step. E.g. my setup is 200 step 1.8° motor, 3mm pitch and a 3.33:1 gear ratio,

Current 3mm pitch ACME screw resolution
 (3mm”pitch” ÷ 200”steps per rev”) ÷ 3.33”ratio” = 0.0045mm per motor step (more than enough)

Ball screw 5mm pitch
 (5mm”pitch” ÷ 200”steps per rev”) ÷ 3.33”ratio” = 0.0075mm per motor step (still more than enough)

Obviously those figures are for a perfect world if there was no backlash, belt lash or leadscrew end play.


I use 425ozin(30.6kg-cm) bipolar steppers by Kelinginc.net with the gearing it has increased the torque to 1415.25ozin(101.898kg-cm) @ approx 110rpm.

Mach 3 is what I use and does not miss a beat, just install a lean copy of XP and away you go. Just get a dedicated PC for controlling the mill and nothing else and you be fine, a touchscreen is nice too as Mach 3’s interface is designed for and Mastercam X for the programming.

I use a Rockcliff 4 axis controller with parallel interface and Break out all in one and a dead synch to setup, although it is open loop as long and you don't try and drive the motors too hard you won't have and positioning issues.

Cheers, Adam.

[holycross]

Doug,

I plan to cnc the 320g. Have the lathe and ballscrews. Still to buy motors.
Haven't had time due to work as well. Looks to slow down a bit next week.
Look to be building some interesting machines.
I'm nearby if you want to meet about the 320g.

Mark

Originally Posted by dmenz Hi Adam, Thanks again for sharing that information. I use my HM-35 manually at present for some heftyish cuts always in mild steel ie facing with a 75mm cutter and 20mm slot drill and slots from 4-16mm in up to 10mm. Even manually, ramping is definitely the key and a CNC conversion would help a lot here. From work projects I have some offcuts from ball screws 20x5 and 20x10 (happy to machine the ends for you if you don't have a lathe). You could have these if they suit and I can get reputable ball nuts at a decent price on my next order if you are interested. Do you have a lathe as I am interested if anyone has CNC'd a Hafco AL-320G lathe or similar? Bit the same here with time have just had 4 projects running concurrently at work but only one running for the next 6 weeks so time to do some capital upgrading My contact details if you are ever NOR, if you can email me a contact number I will give you a call. Regards Doug

[mkc2]

Hi Adam, your not alone!!! There are plenty of perth guys here, Im also looking at converting the x2 mill to cnc, Have already built a cnc router.

Michael

[dmenz]

Hi Kipper, Xasertech (Adam), Holycross and mkc2

I have been busy the last few days but have just had a look at Kippers gallery. Superb work. Very impressed with what Kipper has done on a retro cnc'd machine. Thanks Kipper and Adam for the ball screw suggestions for the HM-35.

It seems like 20dia x 5mm pitch ball screws with 2 or 3.3 : 1 timing belt reduction and a 2 to 3N.m stepper motor will be OK. I guess these are for the X and Y, what ratios and motor torques do you guys suggest for the Z and column? I have a spare license license for Bobvad V19 and the yet as unutilised Mach 3 license and several 20diax5Pitch screw offcuts so all looks good to start with a few clear weeks coming up! Would like to catch up Holycross re the Al320G project you are planning and which I need to do as well. mkc2 that is one of the tidier and finished router I have seen a - I would like to hear what software control you are using in software and what stepper drives and motors you have.

Thankyou all for all your input and good to see Perth has a CNC scene!

Regards dmenz (Doug)

[mkc2]

Hi Doug
Some info on what im using, my drives are RTA (Italy) GMD02 which run up to 6 Amp and steppers are 5.1nm
Attached are the spec's and you can buy local.
Software im using is mach3.

[dmenz]

Originally Posted by mkc2 Hi Doug Some info on what im using, my drives are RTA (Italy) GMD02 which run up to 6 Amp and steppers are 5.1nm Attached are the spec's and you can buy local. Software im using is mach3.

Michael, Thanks, I guess you are using Dean Walker's Automated Motion Systems, superb friendly service. I use Dean's very high quality SD motors and RTA NDC drives when I need a broad speed range. Good choice. Sounds like Mach 3 is highly regarded, I intend to try my license out this coming week. Regards Doug.