Thread: Homann Designs TM20LV CNC conversion

I've been working on the X-Axis ballnut holder. I've finally realised that my mill is based on the RF series. That was what Hoss was referring to earlier on.Maybe it should be called an RF20.

It's slow going working on a 40mmx40mmx70mm piece on aluminium on my Taig mill.

The X-nut holder will be bolted from underneath as this is the only way I can see that the alignment can be adjusted for.

Also, because of the low profile and lack of headroom, the hole in the nut holder will only be 20mm to clear the screw. The nut will not pass through the holder but be bolted to it. I can do this as the nut holder is fastened to the centre of the saddle.

.X-AxisBallnutHolder.jpg X-axis_screw_and nut1.jpg

Cheers,

Peter

Attached is an image of the X-Nut mount. Just finished drill the clearance hole for the ballscrew.

The 20mm Drill bit make quick work of the aluminium.

Cheers,

Peter

The X-nut holder is done. Unless I've made it a mistake.

The holder is 70mmx40mmx31mm. There is a 20mm clearance hole for the ballscrew to pass through.

The ballnut is attached via two M5x0.8 bolts. The holes pass all the way through the holder so I can put another ball nut on the other end if I feel that it is necessary to have a zero backlash system.

I accommodated the original nut's M6x1 mounting bolts. They are on a 50mm pitch. I plan to attach the holder with four M6x1 bolts from the bottom. That way I can adjust the alignment when the saddle is on the table.

You can see the centre punched marks for these mounting bolts in the saddle.

I was a bit worried about the clearance between the nut holder and the inside of the table. I shouldn't have been as there is a lot of room.

I installed the saddle onto the table upside down to test this, and also put on the endplate prototypes to see the fit. All I need now are the ballscrews to arrive and I can do a test fit.

You can understand why I want to fasten the holder with bolts from the underside. I plan to do all the alignment and adjustment of the X-Axis with the table on the bench like this.

As can be seen from the photos there is a lot of clearance. BTW, I need to get shorter bolts if you are wondering why they are protruding.

The mounting on the X-nut holder will have 6 bolts. I've seen some people pin the holder to ensure that it doesn't move.

Any comments on whether I should do this? And if so how is it done? I understand I seen to drill the holes through the saddle and nut holder while it is aligned in place, but I've noticed that some of the pins on my machine are threaded. Is this what I need to do? If so, where do I get these pins from?

The only pins I have are dowel pins. can I use these and press them into reamed holes and loktite them into the saddle.

At this stage I plan to try the machine without pins unless advised otherwise.

Cheers,

Peter.

The Ballscrews from Chai turned up a few days ago. All looks good.

The ballscrew end bearings all slipped on with a nice fit. I had to turn the nuts end for end on each screw to suit the way I'm mounting them. though. I'm glad I asked for the extra balls as I did loose two.

I took a quick shot of the X-axis ballscrew mounted onto the saddle.

When I made the X-nut mount block the centreline of the nut is 15mm from the top and 16mm from the bottom of the block. I did this as I wasn't sure if the screw centrline was 15mm or 16mm from the saddle surface.

From my measurements it seemed line it was 16mm. When I mounted it and put on the endplates it was obvious that 16mm was too high so I flipped the block over and it all lined up quite well. There is some ever so slight misalignment somewhere but that will be easily fixed by providing a little clearance in all the mounting holes.

I put on the end plates and used a power drill connected to the screw to run the saddle back and forth. It showed that the X-axis is going to work, so I'm very happy about that. Unlike the G0704 with its jam bolts, this mill does not have a nut mounting system that provides an alignment system. It all needs to be made accurately, which was not that easy since all the measurements had to be made and are not documented anywhere.

Cheers,

Peter.

Hi Peter,
Looks like they have removed the flange on the nut with an abrasive disc.

Hi Rod,

Yes I think that's how they have done it. I looks very clean though.

Cheers,

Peter

Hi,

The Stand that came with my TM20VL mill is not really suitable. The stand is basically as wide as the mill base and with the 700mm mill table, the hole thing would tip over if the table is positioned fully at either end.

I purchased a Hare and Forbes mobile base W930 | MBW-2 Mobile Base | machineryhouse.com.au that for the mill stand but the whole setup is too unstable. To be fair, If I bolted the stand to the floor it would probably be OK, but I want it on wheels to move it around the shed.

I don't have a welder, nor the time to do much fabrication. In fact the mill CNC conversion is taking more time than I can really afford.

Does anyone have any suggestions?

My current thought is to find something like this, although it is a bit more than I want to pay and may not be sturdy enough.
http://www.bunnings.com.au/products_...lley_2387.aspx


I could then bolt the mill to a base, say 30mm ply that bolts to the top top of the cabinet.

Anyway any input would be great.

Once solved , I may end up with a stand for sale if anyone is interested.

Cheers,

Peter.

These are a couple of other options I'm looking at;

A385 | ETT-1D Engine Tear Down Table | machineryhouse.com.au
T754 | SDC-2D Service Cart | machineryhouse.com.au
T695 | WRC-5D Workshop Series Roller Cabinet | machineryhouse.com.au
T724 | IRC-7D Industrial Series Roller Cabinet | machineryhouse.com.au

Cheers,

Peter.

Originally Posted by phomann

Does anyone have any suggestions?

Have you thought of sending the job to your local fabricator, just a basic frame shouldn't cost too much and will be much stronger than those light bolt together frames. I'd be going with 75x75x2.5mm box section (may be a bit overkill ) ~$100 for 8M when I bought mine.

I'd estimate about $200-350 to get a basic frame fabbed from quotes I've received in the past.

Hi Chris,

Thanks for the reply. I should look around as there must be quite a few fabricators around nearby Moorrabbin as it is a light industrial zone.

Cheers,

Peter.

I really don't think that any of those items you linked to would be strong enough nor rigid enough to give you what you need. The A385 comes closest, but that is only rated at 136 KG static duty. I would be inclined to follow Chris's advice and get one welded up to your own specs. Especially if you can supply the cut steel.

Hi Bob,

Yes, I tend to agree. I guess I'll have to do a bit more research.

Cheers,

Peter

Hi all,

I'm still converting the machine but am looking for recommendations for a milling vice (around 4") that is affordable and suitable for the TM20VL table.
Maybe something like the VK-4 or VK5
Vice - K-Type Milling | machineryhouse.com.au

Their modular vices look nice but a bit out of my price range.
Vice - Modular | machineryhouse.com.au

I'm also looking at some of the vices from Standaco
Standaco - Machinery Sales Australia - Tooling & Accessories

Any info or suggestions would be great.

Cheers,

Peter.