Hafco CNC Conversion

[Johnnysilk]

I have a Hafco HM-35 which I bought some years ago and have now outgrown. I am wondering if this model can be converted to CNC or is it a lost cause.

[chich2]

Hello Jonnysilk,
Im sure you could CNC your HM-35. I have a brand new HM-52 wich I hope to CNC. I don't know where i'm going to start but I hope to get the project going soon. I've seen articles of other people that have done their own machines and seem to have done well.

[Greolt]

Cich2

I also have a HM50 which I am beginning to think might be a candidate for CNC

Keep us abreast of your research.

The biggest hurdle I can see is the knee. It'll need a fairly hefty ballscrew and drive.

I'm in Vic

Johnnysilk, doesn't the HM35 have a round column? That would make it tricky.

Greolt

[Johnnysilk]

I agree. The research I am doing indicates the HM-35 is very do able. I am unsure about the difficullty level of conversion with the vertical axis so I will have to look into that further.

[chich2]

The bloke that lives about 100m from my house does CNC conversions as a full time job. He highly recomends that you CNC the spindle of a Knee mill, not the knee. The reason for this is exactly what you mentioned. The knee is heavy and requires a very large motor. The other problem is that when you initially set up your machine and calibrate the torque for your "Z" axis (up and down) it turns out to be a problem the instant you bolt or un-bolt a heavy machine job or vice. If you CNC the spindle, then it's always the same weight. Much cheaper, easier and reliable AND you can do it to the HM-35 as you dont use the round column. There are many pictures on this forum of people that have done it this way. I have also seen a knee mill that has had the knee CNC'd but I cant see the point.

I hope this has been of help.
Chich

[wjfiles]

The weight of the knee can be offset with a gas lift.
I saw one working in Brisbane a few weeks ago and the Knee could be lifted with one finger.

Bfiles

[chich2]

Progress so far on my mill is that I have decided to do all 4 axis I have. X,Y,Z and A (Dividing head) I now have all 4 DC motors. They are motors from wheelchairs that I have purchased from "babinda01" I orded 4 opctical encoders and shielded cables from usdigital.com and got them within 6 days of placing the order. Very cool! I have to go to Cairns and pick up my groved pulleys when I get a chance. From recomendations from babinda01 he steered me in the right direction to get the right grooved pulleys. I prchased the pulleys through Asscioated World Bearings "AWB" which were exactly half the price of SKF. AWB even worked out details for me. I saked them to supply the smallest plley that would fit my motor shaft, then supply a pulley 4 times the circumference to give me a 4:1 belt reduction, then supplied the center distance I wish to run the pulleys at and they gave me all the info. Pulley sizes and even worked out the belt length! Great service! Oh by the way I used XL series belts at 3/8" wide. Soon I hope to start working on eliminating back lash either via machining another nut to suit my threads and preloading it against the original nut OR machining up a "roll nut" or purchasing ball screws.

Sory for the long post.

Chich

[chich2]

Well I Have finally started the conversion. You can follow the progress at Hafco Metal Master HM-52 CNC Conversion

Chich