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Setting topslide to an angle

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Gordon W11/05/2011 12:10:44
2011 forum posts
I was going to post, and ask how to do this, but I've found the answer! Trying to set the topslide to cut an existing taper, I found it impossible to set the topslide with that last bit of delicacy required to match the taper with dial indicator. Method :- put the tailstock into a suitable position ,then move the cross slide into contact and nudge gently, use the chuck for other direction, of course. For even more control, or to suit your setup, clamp a long bar to the topslide and push against the end. I'm quite sure this is well known, but not to me and maybe some other beginners.
PekkaNF11/05/2011 18:29:35
96 forum posts
12 photos
Good. Now there method of turning the top slide, but how about getting it to a exact angle. I'll get it pretty close with morse tapper and TDI, but what about if the taper reference is miniscule?
 
But If I want to set very close to 8 decree for ER11 holder angle?
 
The ER collets I have are max ER 25 and I'm not convinced they are accurately clockked.
 
I probaly could use Haralod Hall method of two diameter discs of exact distance appart, but it really would excell on more shallow tapper.
 
Any other viable ways? I have tried to find a half decent "metric" sine bar, but haven't got any at my eyes.
 
Thanks,
PekkaNF
mick11/05/2011 18:41:44
421 forum posts
49 photos
For shallow tapers move the tail stock across on its tennons, there should be calibrations on the end of the tail stock body to give you an idea of position. Then place a true bar between centres and clock the fall with a DTI over a measured distance. The sine of a given angle is the fall over an exact inch, so if you are able to set the distance between saddle and bed stop with an exact imperial size spacer which is 2'' 3'' 4'' etc, the longer the better, then you can clock the fall by multiplying the sine value by the size of the spacer. Setting over the tail stock allows you to use power feed over an extended area, rather than using the jurky movement of the compound slide.
Nobby11/05/2011 19:03:45
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587 forum posts
113 photos
Hi Guys & PekkaNF
Looking for a metric sine bar .I use my 5" thats 127 M.M With the calculators we have today, no problem not much good using tables. On the colchester lathe the topslide has a true edge that lends itself to sine bar use.
Regards Nobby
mgj11/05/2011 19:47:51
1017 forum posts
14 photos
You can also do it with a calculator. You measure the rubbing distance for a DTI - the length over which you can measure on your top/compound slide. (Accurately with a pair of calipers)
 
Then you do your basic trig -the leg of the slide is the hypotenuse, and the offset you will measure/set is the opposite.
 
Therefore opposite /hypotenuse = sin theta.
 
So sin theta / hypotenuse = offset to be measured on the clock..
 
If you want to get really passionate about it you can use a genuine DTI rather than a basic clock.
 
Its all you are doing with a sine bar- if you want to pay for one.
Nobby11/05/2011 22:56:13
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587 forum posts
113 photos
Hi Guys
Working between centers. I have a hardened and ground M.T 2 chuck harbor
to set the top slide for that taper . With it set I run a dt indicater along using the topslide handle until it reads zero all the way along then lock the slide. the stylus should be on the centerline. Its worked fine for me I have a super7MK 1 adjustment i find is by tapping the slide with my knuckle.
Regards Nobby
Chris Trice11/05/2011 23:36:38
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1376 forum posts
10 photos
1. Buy a taper turning attachment and do it trial and error using the Harold Hall method or by using a marker pen to see which parts of the male and female taper are in contact.
 
2. If you must use your top slide, fabricate up a post you can fix to your saddle that incorporates a screw threaded rod that can act against your topslide. Or if you don't feel happy about adjusting the threaded rod, slip a feeler gauge between the two to change the angle.
 
3. Clamp a very long piece of steel bar into your tool post and use that to swing the topslide assembly. That at least multiplies up the finesse of movement.
 
In practice, I doubt if you'll get it right first go even with careful measuring. It'll still come down to a bit of trial and error with a test cut. I've got a taper turning attachment and once I got the right angle established, I drilled and fitted a taper pin in an unimportant place so I could go straight to the same angle next time.
Chris Trice11/05/2011 23:41:36
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1376 forum posts
10 photos
Incidentally, you'll get a much better result by using a taper turning attachment and using power feed to draw the saddle along on a fine feed. Turning the topslide handle by hand often introduces just a shade of side to side movement which gives a less smooth surface finish. The slides need to be very well adjusted.
Ian S C12/05/2011 00:23:22
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7468 forum posts
230 photos
For approxamate angles on the topslide for a job that I do that does not require accurasy, I have some bits of sheet metal cut to the required angle, this is inserted between the topslide ane the chuck. Ian S C
mgj12/05/2011 07:04:35
1017 forum posts
14 photos
You can also, with a taper turning attachement, do it properly- the advantage being a very long measuing base leg. 10" on the Hemmingway one. Also I've never moved a topslide by hand when trying to be accurate - I find a light soft faced hammer and a gentle bump to be hte most effective. Light taps and you can apply an offset very easily, and very accurately.
 
I suspect that if one does it trial and error off the scale it is quite easy to get it wrong, because without an accurate vernier life won't be easy. But, over 10" and working to say 1/3 of a thou, you tend to be pretty right first time, for most tapers.
Gordon W12/05/2011 10:12:08
2011 forum posts
Well thanks for all that. I was just pleased to have found the method myself after struggling so much. It's a bit like setting a 4 jaw for the first time. The taper I was copying is an unknown, and was set in a collet so I could copy it, very short ,about 25mm, and finish less important than the angle.
Nobby12/05/2011 15:45:36
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587 forum posts
113 photos
Hi Guys
I know this is drifting awy from the thread. But Ian Ideas Reminds me for setting angles
I"ve made a 45 30_60 10, 15. 18 etc degree setting peices Also 1/2 , 1 , 2 , 3
As Chris says about a taper turning attatchment I will have a go at setting my copy attachtment up to turn a MT2 Regards Nobby

 

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