tapered bore

George just brought up a good point. Any time that I have talked with someone about a taper it was assumed that they were saying the "Included Angle". The "Included Angle" is the sum of both sides of the centerline. In this case that would be 16[SUP]o[/SUP]. You divide the "Included angle" by 2 to set the Top Slide. Thank you George for bringing that up. The print will tell you what to do. If it says "Included" that means both sides, divide. If it is like the one shown by Mike, that is the setting.

"Billy G" :))
 
Definitely agree with George on the protractor. You may get close with it, but for a collet seat, you want as close as possible. Earlier someone spelled out the travel and trig method of verifying the compound angle, and that's as good a starting place as any, but the final word in real life gaging is a ground plug. Since you don't have that, a single line of Sharpie or similar drawn straight down the length of your mating part should smear evenly when you stick it in there and turn it a quart turn or so. When you get that, you're pretty close. Prussian paste is a little thick for this, IMO, and will wipe even with some error in the taper. Ink from a marker is almost immeasurable. But of course, if you do it while it's still a little wet, it will wipe easier. Regular layout dye (Dykem) can be used for this also, as it's not all that thick.
 
I did refer to Dykem,not the thick Prussian blue. Of course,a Sharpie is quick and handy,too. It was I who spelled out the trig and travel method,because it is well for others to be aware of that option. In reality,for home shop use,the insert and twist is faster and quite accurate if you have the personal skill to make teeny adjustments.

Speaking of Prussian blue,I have found that the new water based stuff is quite satisfactory,and nowhere near as messy as the old oil based stuff. I thought we were screwed when the water base stuff first appeared. I bought several tubes of the oil base to hoard!! I did try the water base,though,and it works well.

Do you guys know that it is recommended in the "Machine Tool Rebuilding" book to spread the paste blue with the hand!! It is the only way to get it on thinly and evenly,they said. Probably it's true,too. I use a brayer carefully,or else I'd have to join the BLUE MAN GROUP. Maybe nitrile(not latex,it's full of tiny holes) gloves?
 
george wilson said:
If I were using a protractor, I'd use a more accurate model,like a Starrett,which has a vernier,and nice THIN markings rather than the fat ones on the General. General has always been a "hardware quality" tool maker even back in the 1950's.
Click to expand...

The pic was a file photo just to show the type of protractor. My one is actually a Japanese Shinwa.


george wilson said:
To tell the truth,I usually set the compound as well as I can,taper bore,and sneak up on the final degree setting by boring part way,and twisting the tapered part with some blue on it into the hole. When the blue wipes off all along the tapered part,I know my compound is set correctly,and I finish the hole. It is easier than fiddling around with setting angles that may not actually give perfect results.
Click to expand...

That's the method I intend to use (with a Sharpie) once the taper is deep enough to start accepting the collet.


M
 
jumps4 said:
I would think the diameter of the tapered hole is critical and should be checked often as you cut it leaving room for finishing. it would take very little oversize to set the collet in too deep to tighten at this low angle.
steve
Click to expand...

That's true, but I've tried to allow for that possibility by keep the slug a little longer than necessary until the taper and external thread are cut.

That way, if the pocket gets too big I can take a little off the front end to bring it back to size.
Once everything is correct I'll trim the back end to bring it to the correct overall length.


M
 
I agree, you have 3 options:

#1 -- Set the Top/Compound slide -- Not recommended for a collet taper

#2 -- Use the protractor method -- better but still may not be close enough

#3 -- Do the Trig and use the indicator -- on the money

Billy G" :))
 
Mopar,

Let's not forget that he is copying an existing taper (the collet) so he has a ready made gauge to verify that the taper is correct. On the other hand, if the collet wasn't available, it would definitely be worthwhile to go the indicator route and set the angle dead on.


Tom
 
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George, I haven't tried the water based Prussian yet. You say it's OK though, eh? I'll have to get a tube, as I'm almost out of the oil based I have. I got Richard's scraping DVD, so I'll need to find a few chunks of CI to play around with, so I'm sure I'll need more blue than I have. I have had that paste all over my hands when scraping in a bearing fit. Messy is hardly a strong enough word for it. At least GoJo seems to take it off pretty well.

George, I'm sorry if it seemed that I was just repeating what you had already said. I was just agreeing with you.

I wonder, has anyone taken a good measurement on a collet in it's free state to determine how close it is to the specified taper? I'd like to see it measured on an optical comparator. It may bear on the accuracy of using it for a gage, although probably not to a significant degree.
 
If someone does this with an optical comparator please do more than one collet to check for any deviation. I have access to a comparator but only have ER40 Collets. Probably would do for this test.

"Billy G"

One day I will tell you a funny (maybe not funny) story involving "Prussion Blue"
 
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