Morse taper cut - slide travel too short - need to match cut exactly

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BillWood

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Hello,

Tried cutting my own morse taper a while back and was frustrated by the slide travel being too short and the need to match up the cuts.

I have Hercus 9" an Australian clone of South Bend 9"

I have seen posts where people report its possible to "cheat" and hide the mismatched cuts by cutting a "relief" into the middle of the taper.

3 things puzzle me

1. Does hiding the error in this way mean that the final product is an inferior tool that will only grab over a small fraction of the taper - And this would be highlighted by testing with blue dye and a socket ? Would'nt a tiny discrepancy ie .0001" difference in the 2 tapers mean that one end would "grab" before the other and the thinner cut would be unsupported in the socket ? worst case only 50% of the socket is grabbing ?

2. Any good tricks for "matching up the cuts" that us newbies would like to know about ?

................ and yes I know about taper jigs and offset jigs for the tailpost ........ am really keen to find out if there are any tricks to "matching the cuts"

3 I currently get my best finishes with a shearing tool. Would a shearing tool give a good enough finish to a home made morse taper or would some people use a toolpost grinder ? Again the same problem would exist with the limited travel and the resulting dogleg.


Regards

Bill
 
Hi Bill, as usual I'm probably off track on this one. are you saying your compound runs out of travel? How long of a taper is this? , because I sit here
and picture a MT#2 or 3 such as a common dead center and any S.Bend 9 will handle that just fine using the compound method. And then you could stop
where the compound hits the limit wind it back then move the work. That only will work with a four jaw & dial it in. With patience there will be no line
where you left off they polish it i've done that before. Then the easy way is stick a center in a boring head and dial that in. Everybody hates fiddlin
around with off set tailstocks (I do)... Then you could play with the tool holder (move it over more). There is only one thing, the major and minor
measurement and the distance inbetween....and its not that much, unless you a tapering a truck axle or something. sometimes one has to think
out of the box like using a boring bar to get more travel. Disregard if this dont help I'm more a do'er than a teller...........sam
 
GK1918 said:
And then you could stop where the compound hits the limit wind it back then move the work. That only will work with a four jaw & dial it in. With patience there will be no line
where you left off they polish it i've done that before. T
Click to expand...

thanks GK

I will have a go and see what happens

Bill
 
I have an SB 9 and yes the compound travel is too short to make a taper long enough to fit the tail stock and be ejected when it is retracted. I have cut many MT2 tapers for my tooling I make and it does not need to be ground (many will disagree with that). I polish mine with 600 paper. I use an indicator and precision rod in the chuck to set my angle. If you are careful you can sneak up on the cut and match good enough, but if you make a mistake, do what I do. That is when you cut a relief in the middle. A short relief in the center does not make your tool inferior ( in fact it is possible it will fit better). Another solution I have used is to make the taper as long as the travel and drill the back of my taper, thread it and install and adjustable stop to eject it when the tail stock is fully retracted. I hope this helps you some.

Mark Frazier
 
I don't have a South Bend 9",but I think the compound has pretty short travel. If you have to piece the taper,you'll have to do that. You could do it as carefully as possible and file the finished taper,fitting it in a tapered hole as you go. I usually scribe a chalk line down the side of the taper,wring it in the mating hole,and see where the chalk got smeared. File the smeared areas while the taper is rotating and re chalk and keep doing it till the taper fits all over.

There's nothing wrong with a reduced diameter ring in the middle of a Morse taper. I've seen plenty of commercial tapers with them on chuck shanks,Morse taper drills,etc.. The ring doesn't mean the taper looks cheap. Sometimes the maker will stamp information in that reduced ring,like a brand name,logo,size of the taper,size of the drill,etc.. I guess that's why they use the ring to begin with.
 
george wilson said:
I don't have a South Bend 9",but I think the compound has pretty short travel. If you have to piece the taper,you'll have to do that. You could do it as carefully as possible and file the finished taper,fitting it in a tapered hole as you go. I usually scribe a chalk line down the side of the taper,wring it in the mating hole,and see where the chalk got smeared. File the smeared areas while the taper is rotating and re chalk and keep doing it till the taper fits all over.

There's nothing wrong with a reduced diameter ring in the middle of a Morse taper. I've seen plenty of commercial tapers with them on chuck shanks,Morse taper drills,etc.. The ring doesn't mean the taper looks cheap. Sometimes the maker will stamp information in that reduced ring,like a brand name,logo,size of the taper,size of the drill,etc.. I guess that's why they use the ring to begin with.
Click to expand...

The ring makes it likely that the taper will make contact at two different places and therefor cannot wiggle. It also makes it likely that contact is made near the large end where the leverage is greatest. Since friction is (to a first approximation) independent of contact area the ring does not reduce holding force. IMHO the ring is a feature, not a bug.
 
Good point,John. I will also say that I think the 2 place contact rather than 1 long one will give better friction since the surface area is smaller than 1 long,continuous taper. You want that friction .
 
Thanks for the replies.

Will go and try again.

Am having difficulty understanding that less surface area could be better - attached is a sketch showing how I visualise this inside my head.

Whats wrong with the way I'm thinking here ? In my sketch one end of the taper never ever touches the socket


Bill

mismatch + rebate.JPG
 
Bill,
If you cut the taper as long as possible with your compound, then reposition the saddle and using the cross slide to pick up where you stopped you can finish the taper using just the compound again. I have done this on my Hercus, as well as tailstock offset method.

Cheers Phil

ps are you ex SECV?
 
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