DAPPH
as dyslexik as I'm daft
- Messages
- 6,487
- Location
- Near to Cross Hands Llanelli SouthWales GB
I got an old 1943 ish sphere lathe about this time last year .
i played with it before stripping it to see how it preformed , result all manner of grabbing problems and u adjusted wear showed up .
After cleaning and adjusting ( Timkin taper roller bearings ) the headstock bearings after checking them for wear after 1/2 hrs free running to get them to working temps and clearances there was still problems .
So i went along the lines of tools digging in is usually some form of movement or rocking of tool , the saddle & fittings .
My solutions were :- I had to put a rubbed down flat spacer washer on the cross slide spindle to take up the " 10 thou " jump it often made as soon as the tool tip contacted the work piece & ended up with about 3 thou free movement , which is not now a problem .
I cleaned all the ways and made dam sure there were no dings or nicks on the contact edges that might impede a quality sliding contact.. found that there were a a couple of dings on the back way on the underside by the head stock end . Once the were filed dead smooth , washed off , cleaned & lubed things worked very well . The saddle could traverse end to end of the bed without any sticking tightness or any slopping around I'd also set the saddle gibs to give the best tollerance , then the cross slide gibs and finally the compound slide gibs.
I checked the diagonal slop across the saddle by putting a bar in the tool post, tightened things up as for cutting , setting up my magnetic based DTI to zero when I pushed the bar to the rear of the bed and checked it again when it was pulled forward to the front of the bed
48 thou showed me that the gibs were in need of adjustment so I took the saddle off , cleaned everything , re lubed with slide oil and a bit of grease on the gears . reset the gibs and got 14 thou movement on the re test .
Not much of a problem so long as you lock the saddle to the bed when parting or using the cross slide & compound slide
Fro some reason I still had poor finishing no matter what speed or feed I used on aluminium or steel so I slept on things a while and realised there was not much else to check .
Next check is to take the tool post off , mix a little Biro refill ink with a tiny drop of oil and a tiny drop of meths to give you a quality cheap engineers blue.
Smear the slide side of the tool post and start to tighten it very gently, rotating the post as you go... when it grips stop . Now remove the post and see if the piint of contact is even over both surfaces...it's not un common to find that the tool post bolt has pulled the " Tee slot " faces up because someone has used a simple standard hexagonal bolt and brass washer to do the job when they mislaid the correct part .
My old lathe was a showing a good 11 thou of pulled through face. .
I solved it by cleaning of with meths and then when it was dry using a dead smooth file to file it flat ( putting chalk in the file teeth for the last few polishing strokes ) , giving it a final scrape in a couple of places with a home made scraper made out of a broken hack saw blade that I've ground to a square edge and finished off on my diamond hone stone... after several operations it became a really good face to face mating.
Suddenly all the chatter stopped and all of my parts turned have taken on a good finish .
I'd already purchased a new QCTP & had to use a 4 " grinder to take off the excess metal to get the base " Tee nut " plate to fit the slide with very little clearance . As i set the plate on nthe tool post anchor bolt and slipped it in the slot ...that's when I noticed the pulled through damage.
One other thing I've done is grind ,file & scrape some of the top of the compound slide body off . So that the new QCTP can rotate all the way round without interference . Previous to doing this I had to slacken the locking screws to unlock the top of the slide from the cross slide. Which was a pain if there was work already in the lathe. Now I can just loosen the tool post securing nut and angle the tool post for a quick free angle cut using the compound slide .
i played with it before stripping it to see how it preformed , result all manner of grabbing problems and u adjusted wear showed up .
After cleaning and adjusting ( Timkin taper roller bearings ) the headstock bearings after checking them for wear after 1/2 hrs free running to get them to working temps and clearances there was still problems .
So i went along the lines of tools digging in is usually some form of movement or rocking of tool , the saddle & fittings .
My solutions were :- I had to put a rubbed down flat spacer washer on the cross slide spindle to take up the " 10 thou " jump it often made as soon as the tool tip contacted the work piece & ended up with about 3 thou free movement , which is not now a problem .
I cleaned all the ways and made dam sure there were no dings or nicks on the contact edges that might impede a quality sliding contact.. found that there were a a couple of dings on the back way on the underside by the head stock end . Once the were filed dead smooth , washed off , cleaned & lubed things worked very well . The saddle could traverse end to end of the bed without any sticking tightness or any slopping around I'd also set the saddle gibs to give the best tollerance , then the cross slide gibs and finally the compound slide gibs.
I checked the diagonal slop across the saddle by putting a bar in the tool post, tightened things up as for cutting , setting up my magnetic based DTI to zero when I pushed the bar to the rear of the bed and checked it again when it was pulled forward to the front of the bed
48 thou showed me that the gibs were in need of adjustment so I took the saddle off , cleaned everything , re lubed with slide oil and a bit of grease on the gears . reset the gibs and got 14 thou movement on the re test .
Not much of a problem so long as you lock the saddle to the bed when parting or using the cross slide & compound slide
Fro some reason I still had poor finishing no matter what speed or feed I used on aluminium or steel so I slept on things a while and realised there was not much else to check .
Next check is to take the tool post off , mix a little Biro refill ink with a tiny drop of oil and a tiny drop of meths to give you a quality cheap engineers blue.
Smear the slide side of the tool post and start to tighten it very gently, rotating the post as you go... when it grips stop . Now remove the post and see if the piint of contact is even over both surfaces...it's not un common to find that the tool post bolt has pulled the " Tee slot " faces up because someone has used a simple standard hexagonal bolt and brass washer to do the job when they mislaid the correct part .
My old lathe was a showing a good 11 thou of pulled through face. .
I solved it by cleaning of with meths and then when it was dry using a dead smooth file to file it flat ( putting chalk in the file teeth for the last few polishing strokes ) , giving it a final scrape in a couple of places with a home made scraper made out of a broken hack saw blade that I've ground to a square edge and finished off on my diamond hone stone... after several operations it became a really good face to face mating.
Suddenly all the chatter stopped and all of my parts turned have taken on a good finish .
I'd already purchased a new QCTP & had to use a 4 " grinder to take off the excess metal to get the base " Tee nut " plate to fit the slide with very little clearance . As i set the plate on nthe tool post anchor bolt and slipped it in the slot ...that's when I noticed the pulled through damage.
One other thing I've done is grind ,file & scrape some of the top of the compound slide body off . So that the new QCTP can rotate all the way round without interference . Previous to doing this I had to slacken the locking screws to unlock the top of the slide from the cross slide. Which was a pain if there was work already in the lathe. Now I can just loosen the tool post securing nut and angle the tool post for a quick free angle cut using the compound slide .