Metric Taper Adapter Sleeve

[Royal Viking]

I was not sure where to post my question. I have a taper at the end of a crankshaft that (if I did this right) I measured a change of 2mm in diameter over the length of 10mm. The large end is 22.5mm in diameter. I have a CTV clutch that has a taper of 1mm per 10mm length. The large end is 30mm in diameter. I have to admit that even with the best tools I am challenged to do this right. I had hoped to find someone who may make adapters by searching online. I think I have it worked out to turn the adapter. The first crankshaft failed because the smaller taper did not fit properly (the clutch actually wobbles on the crank when pulled from side to side). I realize already that it may take me several tries to turn both tapers correctly to make the adapter. I have a 9"Southbend and am making a boring bar to do the ID of the adapter.

The adapter looks similar to this:
http://www.denniskirk.com/jsp/product_catalog/Product.jsp?productId=p3842

I bought the project as a basket case in 1993 and I finally have the time to work on it. The crankshaft failed and the owner had given up on it.

Any help is deeply appreciated.

 

[BillTodd]

I would do it this way (Assuming you know what the tapers are supposed to be) :

[or would have done it had I still owned a SB9 ]

Machining the Internal Taper

Part 1 - make an arbour

1 - face and centre drill a piece of steel bar stock for an arbour (doesn't have to be special steel just something that turns nicely - While facing double check your tool height). Make sure it's long enough to hold the adaptor and fixing (see below) with a parallel section to set the external taper

2 - mount it between centres and surface (turn it down) to slightly larger than the maximum internal diameter of your taper.

3 - set the compound slide using a sine-bar referenced to the newly turned arbour blank. Set the angle ready to bore the internal taper (i.e. going in towards the chuck).

This is how Frank Ford does it on his Hardinge copy http://www.frets.com/HomeShopTech/Tooling/LatheSineFixture/sinefixture.html . On a Southbend you'll need to reference to the dovetail (either to the edge or to a gauge pin sitting in the V of the dovetail).

4 - turn down a short section at the chuck end to less than the minimum diameter of the internal taper.

If it isn't a self-holding taper you'll need to find a way to hold the adapter onto you arbour (i.e. thread the small end for a nut)

5 - cut the taper onto the arbour using the newly set compound slide.

6 - check the new arbour (measuring it against the crank taper.

Part 2 - machine the internal taper

You know how to do this

Machining the External Taper

1 - set the compound using a sine-bar as above. Either using the parallel section of your arbour or a test bar held between centres

2 - mount the adapter onto the arbour and turn the external taper - be careful checking the out side diameters (BTDT - several times : )


An alternative, would be to bore the CVT to parallel and press fit a new taper. A friend of mine will have to do this to fit a CVT to a Ducati diesel engine, because the taper on the French made CVT is smaller than the crank.

Bill

 

[Royal Viking]

Thanks Bill!

I was thinking I could get it close and after trial and error get the angle cut (I realized that it could be a lot of attempts as well). I do not have a sine bar at this time. It seems simple enough to set the angle using this method.

I do have the end of the crankshaft that broke off. It has enough of the straight end of the crankshaft left that I can use in the chuck instead of making an arbor.

Could I use the stub end and a dial indicator to set the compound angle? I don't know if that is enough distance to get a proper angle as it is just over an inch in length.

 

[BillTodd]

I was thinking I could get it close and after trial and error get the angle cut

I've used that method once - I generated a lot of swarf :big:

But, having the stub end is really handy

Could I use the stub end and a dial indicator to set the compound angle?

Yes you can do (I have done the same to match the nose angle on my Hardinge lathe, that's about 1 1/2" long). Obviously, it's vital to get the indicator exactly at centre height (ask me how I know ) Tweak it until the needle does not move over the whole length

You'll need to grip the stub in a 4JC and dial it in.

Or, if you don't have a 4JC, use a short piece of aluminium bar stock, as a set of soft jaws, turned with an OD a 3/16" (5mm) or so larger than the stub (don't over-tighten the jaws) , bore it to a push-fit (without removing the bar from the chuck). Push the stub into the new concentric sleeve and the chuck should tighten onto the stub nicely (dial it to check). If you're going to use the stub as an arbour, and I don't see any reason not to, either mark the sleeve carefully so it goes back in the same place, or make another one when you cut the OD taper.

Good luck, and it'd be nice to see picture of the finish item 8)


Bill

 

[Royal Viking]

I have a 4 jaw and I was able to get it within .002" after an hour and a half. The ends where the failure occured on the stub have a raised lip and it made it hard to grip it without it wobbling as well as dealing with the runout. I tried to use a dead center in the tailstock and found that whoever drilled the end for the bigger bolt (the clutch takes a larger diameter bolt) had drilled it off center so that was a lesson in futility. I did put the bolt in the stub and used that to make adjustments (more leverage, less hammer effort, better accuracy).

I decided once I had it that close it was time to stop. I am going to go back and work it out later when I could take the time to get it as close as possible.

 

[BillTodd]

I have a 4 jaw and I was able to get it within .002" after an hour and a half.

Erm...

You might want to watch this:

[ame]http://www.youtube.com/watch?v=2KMhx4DbyDg[/ame]

 

[Royal Viking]

Wow, I am going to have to try that next time!

I can usually get it close in a couple minutes. Not that quick. In this situation it was more like chucking a ball with a nub on the end in the chuck. I had to center the piece in the chuck and then check that the end of the taper was also true. I am definitely going to make a gauge in case I have to do this set up again.

 

[Royal Viking]

Ok, I am just plain slow. After another hour and a half, I have it trued to where the needle is fluctuating less than 0.00025" from the low to high side (about two needle widths if that). The tapered end is also in line with the end that is in the jaws of the chuck. So I guess now I set the compound rest.

 

[Royal Viking]

The pictures here may help with what I am trying to make.

This is the broken stub and the clutch. The old adapter is still in the clutch housing.

This is the crankshaft stub.

I am going to work on it a bit more today and will post as I go. ;D

 

[cidrontmg]

The pictures here may help with what I am trying to make.

This is the broken stub and the clutch. The old adapter is still in the clutch housing.
http://www.facebook.com/album.php?aid=2064025&id=1553071221&saved#!/photo.php?
pid=31275653&id=1553071221
This is the crankshaft stub.
http://www.facebook.com/album.php?aid=2064025&id=1553071221&saved#!/photo.php?pid=31275668&id=1553071221&fbid=1506153624467

I am going to work on it a bit more today and will post as I go. ;D

No pictures seen, just a placeholder icon. I´m not a member of Facebook (hehe, I guess I´m just about the only one on the planet...), so that may be the reason. When I click on a placeholder, I get the login page of Facebook.

 

[GordTopps]

No pictures seen, just a placeholder icon. I´m not a member of Facebook (hehe, I guess I´m just about the only one on the planet...),

No your not........ I refuse to use these type of social network sites.

He He
Gordy

 

[Royal Viking]

Sorry about that. I was hoping it would work as I didn't want to have to manage one more web site login. :

 

[BillTodd]

Why not just attach them to your post here (look for the additional options button bottom left)

Don't forget to shrink them down to 640x480

Bill

 

[Royal Viking]

Bill,
Thanks for the hint. I had missed the more options button.

One more try at the pictures...

The clutch and stub

 

[Royal Viking]

Well I set the compound rest and bored out the inner taper of the sleeve today. I kept fitting the stub along the way and things seemed good. I did had some trouble with chatter and the tool leaving some nasty gouges (I have to do better at grinding the tools). I put the part onto the engine and noticed the fit was not right. It appears that I am slightly off with the taper. When the large end is tight on the smaller end is loose. I've been wondering how I can adjust the slide without getting so far out that I have to start over.

It occured to me that if I had the taper attachment this would have been a lot easier. I am thinking I may be able to make a bracket with a set screw that will slowly move the compound rest. The Southbend has two tapped holes on the carriage that I can use to mount the bracket. I am wide open for suggestions. What ever I do I am limited to the lathe and a small drill press.

 

[BillTodd]

Presumably, your tool was chattering on the larger radius??? If so, I wonder if this has reduced the cut in that area?

(I have to do better at grinding the tools)

Sometimes it is just the tool - I have a cheap 3/8" brazed carbide tool that is basically useless; it sings at all speeds an feeds, yet a similar sized 'eclipse' branded on of similar size is brilliant.

I am thinking I may be able to make a bracket with a set screw that will slowly move the compound rest.

I have a plastic hammer (a 3" x 1" bar of Nylon 6 on a stick) for adjusting things. A gentle tap is usually all that's required to move things a tenth or so.

 

[Royal Viking]

It's a home made boring bar with a round piece of 1/4" HSS tool. I haven't ground a tool in years and I guess I am getting my practice now.

I have a rubber mallet that worked well when I was setting this up. I found that I could easily move things out of place.

I found this last night

the cutting tool must be set exactly
on center with the axis of the workpiece or the workpiece will not be truly
conical, and the rate of taper will vary with each cut

When I began, I made sure the tool was on center. I may have gotten off center as I changed the bit out to try to clean up the finish with a different tool. I guess before I go an do danyhting else I need to check that it was on center.

 

[Royal Viking]

I got back to another attempt at the inner taper today. I was wondering how I was going to attempt this and it occured to me that I could use my dial indicator to track the amount of change I was making to the angle. It was not going to be a precise way but I could get back to my original setting if I had to. It was a judgment call and I went with moving it 0.0025". Turns out that it was perfect! At least as close as I needed to get (what a relief).

The first picture is how I set up the dial indicator. The second picture is the marker showing the contact points. It also fits tight when I checked the stub. I still need to do something with the way I ground the tool as it doesn't seem to cut very well. I though that at this point in time it was a place to stop for the day. ;D

 

[Maryak]

RV,

Looking at your picture of the taper, maybe it's not so much the tool you ground as the condition of your top/compound slide. The gibs may be a little loose and it looks like you are feeding one handed. I'm not trying to teach you to suck eggs but for a better finish when hand feeding, use both hands. The idle hand takes up the load before the working hand has finished and then each is alternately transferred back to a comfortable starting position. It's best not to exceed the comfort level in either wrist before switching hands and try to keep the tool loaded avoiding backlash.

I hope this helps.

Best Regards
Bob

 

[Royal Viking]

Hi Bob,

Thanks for the tips. I had tried tightening the gibs more than once. That didn't seem to help much. Some where along the way I did learn to use both hands to avoid the grooves from stopping the feed (my old neighbor may have taught me that one when I first used his SB lathe). In this case it doesn't seem to matter.

I am cutting from the back side of the work with the boring bar. So although the spindle is not lifted with load could it be caused by the carriage movement (and anything else that may move due to the lifting of the tool)? I think everything is pretty tight but I can check once again.

Roy