Your thoughts welcome
Jonathan Mead | 27/02/2018 21:10:26 |
![]() 30 forum posts 12 photos | Following on from my previous thread about strip down for cleaning, I have made good progress with the setup of the new lathe. Whilst still on the pallet i fitted the Z axis DRO at the back of the bed below the saddle and assembled the stand that I bought with the lathe. With help from my son, the lathe was lifted onto the stand and bolted down, and I could get on with fitting the X and Z1 scales on the DRO system. I then spent a good few hours just turning different materials and getting a feel for what to me is a much bigger machine. Feeling confident, I decided to turn the 11mm shaft for my Hemingway power hacksaw build, which uses ½ inch round bar as the starting point. I had a live centre in the tailstock as the shaft is 5⅛ inches long and I thought it was going well until I measured the diameter at each end. I had 10.98mm near the headstock and 11.24mm at the tailstock end! Today, I set about taking some measurements using the ground test bar that I bought from Warco with the lathe. I set a lever dial indicator up on the cross slide and measured near the headstock and at the end in both lateral and vertical planes:- Zeroed at the headstock for lateral deflection Lateral deflection 0.04mm Zeroed at the headstock for vertical deflection Vertical deflection at end 0.07mm Whilst I was doing these measurements, I noticed that there was a blemish on the spindle face, almost like a small weld spatter that was securely attached and needed removing with a riffler file and some emery. This must have been affecting the alignment of the chuck:- Finally, I did a test turn as recommended in other threads on this site. I didn't have a piece of steel 25mm round bar so used aluminium. Chuck end diameter Far end diameter So the difference between the two measurements is 0.034mm. I realise that I need to shim the bed to try and reduce the variation, but am unsure how to do this on the WM250, as unlike an ML7, the bed has one bolt at the tailstock end and two bolts on the long centreline of the bed under the headstock. Any help/ advice would be welcome. |
David George 1 | 27/02/2018 22:11:38 |
![]() 2110 forum posts 565 photos | Hi Jonathan I would talk to Warco first it's new and under warranty they will have had this problem on other lathes and should help. It's under warranty. David |
Thor 🇳🇴 | 28/02/2018 05:46:14 |
![]() 1766 forum posts 46 photos | Hi Jonathan, Harold Hall has a description of how to set up a lathe to turn parallell, have you checked out his description? I bolted a 16mm thick steel bar under the lathe headstock and tailstock and made some height-adjustment screws on my new lathe - see photo. Thor |
Martin Johnson 1 | 28/02/2018 09:07:27 |
320 forum posts 1 photos | The "Twist the bed until it turns parallel" school of thought originated in parts of Nottingham. But it is poor way of making up for a lightweight flexible bed. However, better quality lathes should have sufficient stiffness in their own bed. The instructions for my Kerry say to undo the bed holding down bolts to finger tight only, and it is supported on wooden shims to let the bed find it's own level. Clearly the orientals think the same way if it your lathe has a 3 point mounting. That being so, you need to contact your supplier and send the photos you have posted here. If anyone has an older lathe with similar problems, you may well find an adjuster under the headstock which will allow the headstock to be rotated on the bed by a tiny amount. (The Kerry has such a device). Use with care, because you also need the lathe to face off very slightly concave (about 0.001 in 10" diameter or so). Hope that Helps, Martin |
Martin Johnson 1 | 28/02/2018 09:09:43 |
320 forum posts 1 photos | Just another thought. Did you check for run out on the test bar when the spindle is rotated? Should not be any on a brand new lathe and test bar, but if there is do your checks at 180 degree rotations of the spindle and split the difference. Martin |
Mick B1 | 28/02/2018 09:13:44 |
2444 forum posts 139 photos | Posted by Jonathan Mead on 27/02/2018 21:10:26:
...I had a live centre in the tailstock as the shaft is 5⅛ inches long and I thought it was going well until I measured the diameter at each end. I had 10.98mm near the headstock and 11.24mm at the tailstock end! ... What I did was turn a 60 degree cone in the chuck from a bit of scrap, then bring up the tailstock with Warco's dead centre in it, and fidget the tailstock lateral adjustment into line as best I could under a 20x magnifier. Over a 3" length, I ended up with diameters of .6978" at the chuck end and .6989" at the tailstock end, or about 0,028mm reverse taper. That's a little over a tenth of yours. I decided that if I come a cross a condition where that isn't good enough, I'll work up a solution for that when it happens. |
Chris Gabel | 28/02/2018 10:29:41 |
2 forum posts | I have a WM250 VF. At one point the runouts became completely wonky. The solution was the Spindle bearing loading nut was much looser than it should be. Corrected this and runouts returned to an acceptable limit. Chris Gabel |
mechman48 | 28/02/2018 13:34:57 |
![]() 2947 forum posts 468 photos | I had similar probs with mine initially, chuck run out was unacceptable, I checked the spindle nose & nothing untoward until I checked the chuck back plate... found a burr the was throwing it out of true, stoned this off & all was well, did a tailstock alignment check, some minor adjustment required. Machined a test piece & mic'd headstock & tail stock ends, within .0045" of ea. other, less than 1/2 thou"... good enough for me. |
Howard Lewis | 28/02/2018 16:43:03 |
7227 forum posts 21 photos | No lathe with twist in the bed will turn parallel. Without using the tailstock, clock the Alignment Bar, (preferably using the Morse Taper, if it has one) at each end of the bed and adjust the feet of the lathe, (Adjust with nuts or shims) until you are happy with the results. THEN, you put the Alignment Bar between centres (trim them up before use!) and check to bring the Tailstock centre into line with the Headstock centre. Then you can check that the Headstock and Tailstock centres are in vertical alignment.(DTI or trap a 6" rule, Razor blade between the centres; it should be vertical) When all is acceptable, you should then be able turn parallel. Howard |
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