Anyone willing to make me a Spindle Post ?

[rafezetter]

I'm hoping one of you with an engineering lathe will be able to help me; I'm in the market for a metal spindle, that isn't too complicated hopefully, but I don't have either the machinery, (or skill) to make one myself.

It will need to be stepped to the below dimensions:

top section 12.5mm diameter (to fit into a 1/2 router chuck) - length 30mm
middle 10mm diameter - length 35mm
bottom 6.?mm (I want to make an expansion fit joint to a 6mm hole) length 25mm with the last 5mm tapped to take an m6 nut.

it's going to need to be out of steel able to spin at 8000 rpm (max) without any distortion under load. The central section is for a 29mm bearing sleeve mounted to a frame, so that should harness any vibration caused by the length.

Anyone fancy taking a stab at quoting me for this? No rush.

 

[dickm]

top section 12.5mm diameter (to fit into a 1/2 router chuck) - length 30mm
middle 10mm diameter - length 35mm
bottom 6.?mm (I want to make an expansion fit joint to a 6mm hole) length 25mm with the last 5mm tapped to take an m6 nut.

Anyone fancy taking a stab at quoting me for this? No rush.

Can't offer to make it, but not entirely clear what the dimensions/nature of the bottom bit are. You say "expansion fit" in a 6mm hole, but to fit that, the shaft would have to be <=6mm, not >6mm.
Or am I misunderstanding completely?

 

[rafezetter]

What I mean is the spindle be marginally larger than the 6mm hole that is already there, so that when the metal section with the hole is heated (and possibly the spindle cooled), the hole expands enough to drive the spindle in, and when it's cooled it clamps down on the spindle rock solid (or at least that's what I'm led to believe).

 

[chaoticbob]

Hi rafezetter. That's the principle, but it's actually not so easy to get it right - if you don't have the setup to press the parts together quickly, the bit with the hole cools too fast and they lock together prematurely, never again to come asunder. You can guess how I know this...
Have PM'd you,
regards, Rob.

 

[rafezetter]

Hi Rob, got your PM thanks, have replied. For the putting together bit... I was going to hit it with a hammer although I had read if they don't go together in one go, you are fubar'd.

 

[thething84]

i know this is an slightly older supject, but you can heat the bit with the hole while at the same time freeze your mandel. That way the mandrel will shrink slightly and your part with hole will heat. To be honest we do alot of freezing in bushes and the interference fit for the holes we use in Alluminium is +0.0003" to +.0015". Hope this makes sense. So in order to get it right your really need to get as accurate a measure on your hole and then make your mandrel a slight interference on that. May be slightly more inteference than what i put above due to being steel. We use Liquid Nitrogen to freeze in bushes as we do not heat the part they are going into.

Hope this helps.

James