Thread: Weiss VM32 Mill Conversion
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31-01-2019 #1
Weiss VM32 Mill Conversion, 1.5kW brushless motor belt driven design. Large 840 x 210mm table with 525mm X movement and 220mm Y. Z travel is 370mm assisted with a gas strut.
This mill was purchased from Toolco under the VM32B name or is available from Amadeal. I spent a lot of time at shows and suppliers before settling on this machine, which I think is a very good candidate for conversion, as well as being an outstanding mill. By far the hardest part of this project was getting hold of the mill.
Disclaimer - I have no connection to any of the suppliers mentioned in this thread or anywhere else come to that.
Built the stand as shown in picture 1. silver rails are drawer runners for mill parts. Centre section houses drivers power supplies and electrical stuff. Kitchen worktop in picture behind forms worksurface.
The big day finally arrived and I was left with a large box on my drive (2).
Removing the box revealed the mill and accessories covered with a transparent bag (3)
Bag and bits removed revealed the mill. Inspection revealed no transit damage (4).
Connecting strops under mill to allow a safe and stable lift (5).
Test lift showed all Ok. (6)
Finally onto the stand with no dramas (7) :-).
Next installment soon.
Best regards
picclockLast edited by picclock; 31-01-2019 at 10:21 AM.
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02-02-2019 #2
Nice work. Warco also sell that machine or similar and it has been on my consideration list for some time. Having a CNC router is great but sometime a quick bit of manual machining, especially steel, would be handy.
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03-02-2019 #3
Hi routercnc
I visited the Warco factory on their open day, primarily to check out the WM18. The main difference is that it is gear driven and has a less powerful brushed motor. I am sure the ones I looked at had a different base casting to the one shown on their site. Having a belt drive is important to me. Its quieter and when it fails you just replace the belt. I also have a smaller WM14 mill from Warco, which has had broken gear issues. It is far noisier than the 1.5Kw belt driven VM32B despite being only 600W. I did snag a fairly decent vfd lathe while I at the show, but for me the WM18 did not meet my requirements.
Once I had tested the mill to make sure it functioned correctly I proceeded to disassembly. This started with removal of the table end cheeks and threaded x screw. The tapered gib was removed and the table removed. The original X Axis bearings were kept as I plan to reuse them. Removing the table was easy enough but it is heavy. This I slid onto a workmate. The saddle was similarly removed. Both castings were of excellent quality.
I am fitting ballscrews to all three axis, but I think I made my first mistake here. I assumed that because the leadscrew diameter is 20mm that replacing it with a similar diameter ballscrew would be the easy option. The snag is the size of the ballscrew nut which is far larger that the original - oops!.
I have read about machining ballscrew nuts with carbide mills. My advice is don't bother. I took a brand new 12mm carbide mill and attempted to make a small test cut 0.25 mm deep and 0.25 mm wide. The end result after a very short distance was a very blunt endmill. So I attacked it with an angle grinder with very good results. It is very important not to let the nut get hot or it will lose its temper, so cooling with wd40 or similar is a must, with long pauses between grinds.
To work on a ballscrew itself you need to have a lathe with a spindle hole large enough for the ballscrew, a 4 jaw chuck, a custom collet, headstock centering bush, and a nut bearing keeper. The ballscrews for my machine are all 20mm x 5mm pitch. They were bought with the ends machined (BK/BF15), so if you do this you must remember the length quoted by the sellers includes this. The threaded end is 60mm and the other is 13mm, so ballscrew thread is length quoted - 73mm for 20mm ballscrews.
As a guide the lengths needed for this machine are X=840 table length+end cheeks@30mm each (depending on what you do with the free end). Y= 450mm (inc ends), using a 10mm plate for the thrust bearings. Z = 650mm inc ends.
The collet is simply a length of aluminium tube to fit the ballscrew. This is cut to the length of the jaws in the chuck plus a 2 cm. Four slots are cut in one end to just over the length of the jaws. When fitted over the screw it can be clamped without marking the thread.
The centering bush is just a piece of aluminium bored to the screw OD and made with a shoulder. Approx 2 cms long should do. This is placed on the end of the screw protruding from the spindle and can be fixed in place with the ballscrew nut or a suitably sized oring. It jut stops the end of the screw whipping about.
The keeper is an aluminium cylinder, drilled through 6mm clear. The ends are drilled 10mm to a depth of 15mm or so. The outside diameter is 18mm.
The conventional method is to use deep groove ball races for the axial thrust at the ballscrew ends. This BK/BF system uses two races in which the outer part of the race is spaced apart and the inners compressed until they rotate with little axial movement. balls used in this way run on the edge of the grooves in the casing, which makes me unsettled. Using a thrust race for axial loads the ball is fully supported by the machined recess in the support washer, so a much larger area of contact is used.
In order to use the thrust races the diameter of the ballscrew end needs to be reduced to 12mm for the 51201 thrust races. These have a load rating of 13.3kN, which should just about doThe end will be tapped M12x1mm for the clamping nut which will preload the bearings. The nuts are simply made out of 1" bar stock, drilled and tapped in the lathe, with the corners rounded to an OD of 28mm. They are 8mm thick and after parting off the corners are drilled and tapped 3mm for a locking grub screw.
Thats all for now
Best Regards
picclock.Last edited by picclock; 06-02-2019 at 10:13 AM.
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03-02-2019 #4
My experience with the conversion of WM18 is that I used 16mm screws with double nuts and used AC bearings.
I am helping someone do another one (purchased about 8 months ago) and was surprised just how much that they have lightened the table and saddle castings...Clive
The more you know, The better you know, How little you know
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03-02-2019 #5
I'm converting a similar machine from Chester Machine tools and found it's fairly cheap (around £5 each) to replace the lead screw end bearings with a quality brand from my local industrial bearing & seal supplier.
Don't forget your oil delivery system to the ball nuts, it will significantly increase their working life.
- NickYou think that's too expensive? You're not a Model Engineer are you? :D
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06-02-2019 #6
Y axis start.
Picture 1 original X Y acme screw nuts
picture 2 Ballscrew mounts on saddle. These are 15mm thick (from scrapbox) but 12mm should work.
picture 3 Saddle with nut fitted. To fit to the mill base the mounts/nut must be removed from the saddle to the keeper(post 3 picture 7). After screw is located into the base, the nut and mounts can be attached. The keeper has a 10mm recess to fit the turned down end of the ballscrew to give alignment. The saddle can then be fitted and attached to the mounts with original 8mm screws.
picture 4 Y axis ballscrew mounts
picture 5 Y axis top view. All y axis parts are 10mm mild steel.
picture 6 Y axis plate dimensions.
picture 7 Y axis sides for motor mount. Length may be altered depending on coupling ans shaft lengths.
Thats it for now
Best Regards
picclockLast edited by picclock; 06-02-2019 at 12:29 PM.
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06-02-2019 #7
The 'conventional' method should use angular contact bearings, not deep groove bearings, which are far more suited to the purpose than a standard thrust bearing.
A basic thrust bearing gives very little radial support, so unless they're housed and adjusted perfectly, when spun at any speed your shaft/ball screw will likely whip, resulting in the kind of issue you are attempting to avoid. Any play in an angular contact should be noticeable in backlash long before damage from whipping become an issue, unlike a basic thrust bearing.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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07-02-2019 #8
Really nice thread Picclock, been looking forward to this for some time.
I'm getting mine through Hugh at Amadeal - he has been really great to deal with. He has ordered it direct from the Weiss Factory, hopefully it will be arriving April. The Vm32L or VM32B (same machine) are not the same as the AMAT30's - these are made from a different manufacturer apparently.
Unfortunately I believe the owner of Toolco lost the contract with Weiss Machines - The owner of Weiss said he went in for an operation and not been heard from since :( I hope he is OK.
I too will be converting to CNC and will be watching your thread closely -
I may have to pick your brains too - I have already been chatting to Clive S loads - he's been great and has loads of patients with my noob questions.
keep up the good work
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17-02-2019 #9
Slight project deviation today. Glass scales.
Are pretty much the best choice for these classes of small machines. They have excellent repeatability and do not drift with temperature or time. The snag is that you must order precut sizes, which is a problem because the delivery times from china are long. A simpler approach is to order the scales as long as possible and then shorten for your application. This also has the advantage that if one gets broken its easy to make up a spare. I have done this many times and evolved a good method for doing it..
Scale construction :-
The scales are enclosed in an aluminium extrusion with caps attached at either end by 4 crosshead screws, around PZ0 size. These can be removed to access the interior. The long strips of rubber/neoprene are dust seals. They are handed, the lower side having protruding lines of material to help the seal maintain the correct shape. The interior read head straddles the glass. One side is spring loaded to ride on the top and side of the glass scale with small bearings, the other side is automatically spaced on the opposite side, think inverted U. The bottom of the extrusion is asymmetrical and the scale itself is butted to it, and held in place by silicon rubber and nylon spacers placed at intervals. The end of the glass scale finishes approx 1 cm or so (min 4mm max 12mm) before the end of the extrusion. This is to give clearance for the end cap and is not critical.
To shorten you will need a tap and drill for the end screws, a BS1 centre drill and some general workshop tools, clamps battery drill, vice etc. . The end screws are generally m2 or m2.5. I will generally fit M2.5 as they feel more secure to me (we all have our foibles :-)). Firstly remove the end cap and read head. Place the read head and cable somewhere clean for later. Slide out the seals, or just remove the other end and pull them out of the way. Next cut the extrusion/glass to the travel length+80mm(read head)+ min 20mm overtravel. I have found the best way is to use my 6x4 bandsaw with the open end of the extrusion facing away from the motor so that the open edge gets cut last. The lower face of the extrusion should be the one that supports the glass. See pictures. Next take a pair of 1/2” pliers and break the end 4-6mm off of the glass. Its important to bend the glass away from its supporting edge or it will break longways. This glass is really soft and breaks very easily, you can even just crush the end. Remove the debris and place the extrusion in a mill to square up the end.
Next drill and tap the threads. Put a piece of square bar stock onto a bench vice and clamp the extrusion to it gap upwards, leaving 1 cm or so of protruding stock. Once secure the end piece can be fitted and clamped in position. Use a battery drill with a BS1 centre drill to a depth of a 1-2mm or so. Remove the end and proceed to carefully drill and tap as normal. Its only necessary to have a short length of thread, determined by the length of the screws protruding from the end cap. Small taps and drills are easy to break, so be gentle. Use lubrication on the tap, molybdenum grease or similar. Unclamp the extrusion and clean away all debris (I use an airline for best results). Refit the rubber seals making sure they are fully abutted to the other end cap and cut flush to the extrusion end using a razor blade. Refit the read head, and end cap. Job done.
Whilst we’re on scales a quick mention of wiring. There seem to be two standards of connections for the 9 pin D connectors. Seemingly designed to stop you using one read head with a different controller. I have only found two but there may be others. I have successfully altered the interior connections on one of my readouts to accept both types and they are electrically compatable. All my stuff is 5V so I don’t know how this would work for 3V stuff. See drawing.
More stuff soon
Best regards
picclock
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17-02-2019 #10
It might be worth copying all that useful info to a new thread with an appropriate title in the appropriate section, that way anyone surfing the forum or searching for that kind of info in the future stands a greater chance of finding it. ;-)
NickYou think that's too expensive? You're not a Model Engineer are you? :D
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