Out of interest how do you lap a taper?
- Thread starter dan.taylor.1
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Same way you’d lap anything. You would want tooling that is accurately ground to mt3, but which will get almost right to the bottom so it doesn’t leave a step (but not so close to the bottom that it fouls on the end) You couldn’t use an old drill because the tapered shank isn’t long enough, it would create a step and potentially stop drills from driving into the taper.
If it were me, and I was confident my lathe was accurate, I’d turn a tapered plug to mt3 size. It’s easy to clock to a pre-ground tool to get the correct angle on the compound slide. I’d then set up a tool post grinder and finish the taper then put a tee handle on it and use some fine grit paste. Three or four slots along the length would be nice but not essential for the minimal lapping required here. 10 mins and that’ll be like new
I agree a reamer could easily make that worse.
If it were me, and I was confident my lathe was accurate, I’d turn a tapered plug to mt3 size. It’s easy to clock to a pre-ground tool to get the correct angle on the compound slide. I’d then set up a tool post grinder and finish the taper then put a tee handle on it and use some fine grit paste. Three or four slots along the length would be nice but not essential for the minimal lapping required here. 10 mins and that’ll be like new
I agree a reamer could easily make that worse.
dan.taylor.1
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dan.taylor.1
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What grade do you reckon. Medium? Or do I stretch to the kit?
dan.taylor.1
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The list that seems backwards you mean?! Coarse leaving a fine finish and extra fine for roughing....
dan.taylor.1
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Medium ordered. Is it just a case of a little smear (once I've mixed it as that stuff is a dry powder to mix with oil) along the taper and rotate back and forth, whilst pulling in and out, similar to lapping engine valves in?
Apply a light coat to one surface (although it’ll be easier to coat the lapping tool) then shove it in, light hand pressure pushing the tool into the quill and give a dozen or so turns in either direction between 10 and 2 o’clock. Turn lapping tool 90 degrees and repeat. Do this two more times and lift out, clean and inspect. If more is required apply more compound and repeat.
I’d take the quill out and put it in a vice. Just make sure you don’t spend too much time in one direction, move the lapping tool around to keep the material removal even. Don’t be tempted to put the lapping tool into a drill and spin for ages in one direction, that’ll do no good…
I’d take the quill out and put it in a vice. Just make sure you don’t spend too much time in one direction, move the lapping tool around to keep the material removal even. Don’t be tempted to put the lapping tool into a drill and spin for ages in one direction, that’ll do no good…
Probably less oily than autosol as well.Toothpaste also works
https://www.amazon.co.uk/s?k=eucryl+toothpaste&sprefix=eucr,aps,150&ref=nb_sb_ss_ts-doa-p_5_4 - for a bit more bite
addjunkie
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Im obviously older than you, back in my day Brasso was the kiddie for finish lapping or even jewllers rouge if your were really going for it!
dan.taylor.1
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Right, have lapped this 4 times with blue in between, and I think im going to leave it as is now as there's pretty good contact all round now.
I'll see what it grips like back on the lathe, it isn't difficult to take out again if needed.
I'll see what it grips like back on the lathe, it isn't difficult to take out again if needed.
dan.taylor.1
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Here's the tool I made, cut the tang off a new MT4 Arbor and tacked on a bar. You can see from the grey area it's pretty uniform.
dan.taylor.1
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The stuff you said. Time saver or whatever. Took it's time getting here mind!!
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