# I need to make a tapered mandrel.  Material choice?



## Cavediver (May 10, 2017)

I'm trying to finish up the restoration of a 40's era jointer.  The pulley end of the cutter head is chewed up due to slipping setscrews and whatnot, so I intend to turn it between centers and clean it up a bit.  As that part of the shaft will no longer be a standard size I'm going to need to make a pulley with a custom bore.  As I understand it, the best way to do that is to mount some stock on a mandrel and turn it between centers.

So:
Should I start with a purchased mandrel and turn it down, or can I just go at it with the nearest-sized bar stock?
If I make the mandrel myself, is there a good / better /best material choice, or will plain home-center steel bar work just fine?

This will be turned on a mini-lathe with user-ground HSS tooling.



End-note: This is an experience project for me.  Like many other things I do, it'd probably be a lot faster and cheaper to send this job out, but where's the fun in that?  I'm just planning this at the moment; right now I  need to figure out all of the things I will have to do in order to even start this project, including getting my tail stock tuned up (a job I've been putting off for a while now...).


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## Zathros (May 10, 2017)

Usually Carbon steel but that's hard to work with, stainless steel night be à alternatieve. Or Swatch for à step up adapter. They are available for mk/mt and Some others so I would guess it Will be also for your tool.
Alternative is titanium, you need hard metal to work with and also your tools.
Hope it helpt à Tiny bit.
Grts
Ted


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## woodchucker (May 10, 2017)

It should not be too hard to create one you have to realize that the taper on a mandrel is just a few thou. You don't want the piece only touching one edge and not being fully supported in the bore.
I have a bunch of taper mandrels , mostly .5 and less, a couple larger for a project or 2. I realize you want to make one, but the cost of buying is not expensive to buy just one.
But since you want to make one.  And it will be for a single use? Mild steel might work ok.  Since it will be steel on steel, use some oil or anti seize when pushing it on so as not to gall it.
Lets say your bore is 7/8   .875...   you will want a taper mandrel of lets say 8 inches. center drill it and put a flat on one side.. That will be your widest side, since you want to cut toward the chuck and to widest side, so it pushes onto the mandrel, not off of it.
Your narrow end should wind up being .873 your widest end .877, so it should slip on without a problem, and lockon in the middle at the .875 range. Polish the mandrel so it is smooth as silk. upto 1200 or so grit so the part does not get permanently locked on.  use an arbor press or hydraulic press to just push  it on a little.  Use the flat to mount the dog and go to work.

Now if you are building for re-use, you need to choose a better steel. I would think a steel that can be hardened would be best. the ones I have bought I don't think are all hardened. I got a bunch on flee bay, and some are damaged by a cutter, some by pressing too far. All appear to be ground originally.


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## Cavediver (May 10, 2017)

This will (likely) be single use.
I would love to buy one, but I only want to take enough off of the cutter head to smooth things out; I don't want to take enough off to drop down to the next available size if I can help it, though that may very well be what happens in the end.


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## 4ssss (May 10, 2017)

This will give you an idea of what to make. You can buy a motor shaft adaptor like the ones here on flea bay.

http://www.ebay.com/sch/Industrial-...pters-Bore-Reducers/181781/bn_16563177/i.html


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## woodchucker (May 10, 2017)

Cavediver said:


> This will (likely) be single use.
> I would love to buy one, but I only want to take enough off of the cutter head to smooth things out; I don't want to take enough off to drop down to the next available size if I can help it, though that may very well be what happens in the end.



Hmmm. I read pulley and not the whole cutter head.
If you are trying to load the entire cutter head on the mandrel, I don't think it will work. Tapered mandrels are meant for short objects. Long ones, will require an arbor. Most cutter heads already have their own centered shafts integral to the cutter head. They are mounted on pillow blocks.

Can you shoot a pic ?   if it's what I think, just remove the blades, mount it between centers and just friction hold it, to smooth it.


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## mikey (May 10, 2017)

Cavediver, you can use plain mild steel as a mandrel to turn the pulley. An easier option would be to find a pulley with a small bore and then bore the center hole to the size you need.


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## Jimsehr (May 10, 2017)

Cave diver 
As a machinist with over 60 years machining things. I think you would be a lot better off by fixing the screwed up shaft then making a new pulley. You can turn it down and sleeve it. Or build it up with weld and return it to whatever size you need.
It's easier to turn the shaft then to make a new pulley.
Jimsehr
If you weld it up make sure the weld is machinable with your lathe.


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## cjtoombs (May 10, 2017)

If you only plan to use it once, mild steel is probably the way to go.  Depends on what you have laying around, too.


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## Tony Wells (May 10, 2017)

I'm going to agree with Jim. By the time you build a satisfactory mandrel and do the roughout to prep the sleeve for the mandrel, you could have repaired the shaft 2x. When you are done, you will have restored the cutter head back to factory dimensions and keeping things running true. At the speed joiners run that is pretty important and will be easier working the OD of the shaft than messing with bushing a pulley and keeping everything true.


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## Cavediver (May 10, 2017)

Thanks folks.  Good food for thought

Unfortunately, I don't have any welding capability at this time, hence my thoughts at the process I posted.  The reason the shaft needs to be repaired, at least in part, is due to a prior owner using shims or a sleeve in a standard bore pulley.  They did a terrible job with it and tried to compensate with a pointed set screw... 

That didn't work.  

The cutter head and shaft are one piece, so my best guess was to turn it down enough to get a good match with the pulley and work from there.  Due to the rotational speeds of this thing (4K+) I wanted to avoid taking off any excess material and hopefully preserve the strength of the shaft.  



woochucker said:


> ...
> Can you shoot a pic ?   if it's what I think, just remove the blades, mount it between centers and just friction hold it, to smooth it.


I can, though I think you have the right idea.  It started life as a single bar, turned, milled, and drilled.


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## Silverbullet (May 10, 2017)

You need t make a mandrel to make a pulley ?  How big is the pulley ?  Mandrel doesn't have to be tapered to do your job. If you chuck up a larger piece of stock steal or aluminum , turn the bore size just so it's a little tight to push on , drill and tap the stock to say 3/8- 16  or 24 . Then with a thick washer bolt the pulley material to your now mandrel , if need be the shaft can be cut short so the bolt holds tighter even. With out taking it out of the chuck it will stay on center no mater any run out it will be on center.


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## Tony Wells (May 10, 2017)

You just need to skim the shaft between centers to get nearly a full cleanup, with a generous radius where it meets unworn area. Then take a piece of steel stock large enough to machine down to match a new pulley, bore it to fit very close to whatever size you ended up with on the existing shaft and perhaps even shrink it on. Just part it off at that point. Heat the sleeve, freeze the shaft.  Once you have it on and it's stable, back between centers and finish turn the OD. If it makes you more comfortable, drill a dimple thru the sleeve into the shaft for the set screw. HOWEVER..... 


My 1947 Delta has a keyed shaft, if I'm not mistaken, so there is a complication that requires a slot to be cut in the sleeve. Only has to be as long as the key, if there is one though. Hopefully, the shaft isn't so damaged that you end up machining it down enough to lose the keyway.


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## Cavediver (May 11, 2017)

No key on this one, just a chewed up shaft!


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## 4GSR (May 11, 2017)

I would cut the shaft off, drill and bore a hole about 1" into the cutter head, bevel the edge with a good weld bevel.  Then make a oversize stub shaft that would be a slip fit in the hole, even a slight interference fit, weld it in place.  Last machine the new stub shaft to size.


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## 4ssss (May 11, 2017)

Turn it down, shrink a bushing on it and turn it back to size.


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## benmychree (Jun 2, 2017)

I might (if I were you) take the head to a weld shop and have them build the shaft up with weld probably Tig weld with mild steel, bring it home and chuck the good end carefully for concentricity with the bad end held in a steady rest, then recut the center to make sure that the weld did not warp the shaft, then support it with the center and recut the shaft to the original size, and key it, then make or buy a new pulley, or possibly sleeve the old one if there is enough thickness to allow a sleeve that has enough wall thickness for a keyway.
Recutting the center is done with either a tool that can be adjusted to the correct angle (30 deg off the center line) or a center reamer (looks like a center drill with no straight portion, just a sharp point) a center drill will pretty much just follow the old pilot drill, but one can be held in a boring bar holder with the lips horizontal and be used like a boring tool, set out to enlarge the existing hole, then be set on center and be used to ream the center back to concentricity.


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## KBeitz (Oct 15, 2018)

Lathe a tapered hole in your pulley for an H bushing and your problems will go away...


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## Silverbullet (Oct 18, 2018)

Fix weld up the shaft and turn to size needed. Then I would use a woodruff cutter and use the size needed for pulley . Moon keys are better then straight type in my opinion . At least for this type of machine .


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## MarkM (Oct 18, 2018)

Here s a mandrel I made.  I couldn t get something dialed in and also wanted to add to the shop so I came up with the idea of a press fit of friction drive and also to be able to place it with the spacers where I want it.  Taper of 9985" to 1.0015".  Moved the tailstock over before finish size to come to this taper.  Used it a few times now.  I had the stainless off a propshaft given to me so cost me my time.   There s a bushing I used for a press fit and the larger boss as well a press fit.  Didn t have the stock diameter so had to use plate for that one.  So if you make one it s going to be a project so I d go the easy route and turn it down and bush the shaft.  Easy peasy!  Or have fun with a mandrel project.


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## P. Waller (Oct 19, 2018)

How do you turn a bore with a mandrel and tail stock in the way?


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## MarkM (Oct 19, 2018)

I offset my tailstock to turn the taper on the shaft.  The nut and washer for pressure with the right combination of washers for spacing. For example I can use a bushing like the one on the shaft for a brake drum where the bearing would go.  Like i said earlier it was to be able to run true.  This was a 42 ford pickup brake drum with a hub rusted and missing a lug bolt.  I didn t feel comfortable the way the jaws clamped the cast hub so that s what started that project.  Customer was a mechanic and said he would deal with the hub. A can of worms for sure!  I can also use it to inspect something with a slight lose fit spaced accordingly and also sqeeze something to turn.  That shaft with the two collars and the 60 degree shaft beside is used to put the tailstock back true.  Rather than take the chuck off and use a dead centre i ll recut that 60 degrees each time and run that shaft between centres and take a cut of each collar and measure. When the same it s straight.  I just use friction drive off the dead centre and take a very light cut.  The vfd with soft start helps with that.  You may have to take your chuck off and and put the dead centre in if you keep fighting the polish from the abrupt starts and spins. Maybe not. I first used a dead centre in the tailstock then checked my live centre. Same measurement again so all good now for accurate cuts.


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