Bushing sizing question

[SPiN Racing]

Hey guys.. I have a question.

This is a question best answered from a practical point of view.

On my peck drill.. I am putting a brass bushing at the snout of the thing. I am going to go for 1.5" or 2". I need to verify the material and length I can use... but thats what Im aiming for.

Here is the question.
What sort of interference do I go for? Or do I?

If the bar sliding through it is .750" for example....  do I make the opening .750" ??  Or 749? 755? 745? 730?

Do you make it the same size? Smaller? Bigger?

I looked at the tailstock repair you did John, on the other forum, but I didnt really percieve if there was a difference....

Also I am planning on using brass... Should I use Bronze? (I will need to go buy some)(I dont know enough to know the good or bad difference in bushing material)

Thanks guys.

PS.. I ahve made a lot of progress on the peck drill. Just have been slammed and no time to do a update.

PSS... I have videos too.. that need compiling..

[sbwhart]

Hi Scot

You machine to give a small amount of clearance by making either the bore slightly big or the shaft slightly small:- for what you're doing you want about 0.001" to .002" clearance to give a nice sliding fit, don't make the bush to short, the longer the bush, the better the location with the less play in the bar.

Have you got a 0.75 drill ?, if yes try it on a test piece you may find its cutting oversize enough to give you a good fit on the shaft, if not you'll have to bore it out to fit. Use a good stiff boring bar and when you start to get close to size feed the cut through a couple of times at the same setting to get rid of the spring in the bar.

Brass or Bronze will be as equally as good for that application

Good Luck and have fun
 
Stew

[bogstandard]

Spin,
On something like that, I would bore to what I would call a snug fit. About the tolerance Stew was on about. I would class 'snug' as a smooth sliding fit with no wobble between parts, if anything a little on the tight side but not overly so.

You have to be careful when you make sliding bushes, it is all too easy to fit them into position then find they have compressed up so they don't slide any more.

You might be better to fit the unbored bush into the fixture first, then bore it out to accept the sliding part.


John

[SPiN Racing]

ooh good idea.

I can use the godzilla loctite I have to get it in there for the long haul as well.

(SWMBO banged her replaces knee on the car door last night.. so I am staying up to take the boys to school. I will try to post a pic of the wild use of heavy duty loctite.)

Thanks again John for the advice 

Scott