I need to make a tapered mandrel. Material choice?

Cavediver

Cavediver

Registered
Registered
Joined
Jan 9, 2016
Messages
120
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...).
 
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


Verzonden vanaf mijn iPhone met Tapatalk Pro
 
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.
 
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.
 
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.
Click to expand...

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.
 
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.
 
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.
 
If you only plan to use it once, mild steel is probably the way to go. Depends on what you have laying around, too.
 
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.
 
You must log in or register to reply here.
Back
Top