Mandrel Question

[GL-P]

What type of mandrel do you use?

I've narrowed it down (or not) to these:

Steel-cheap, able to turn down to size
Aluminum-able to turn down to size
Polypropylene-epoxy doesn't stick well to it
Polyethylene-epoxy doesn't stick well to it
Delrin

I need to be able to accurately turn them down to 24mm OD for my motor.

Any suggestions? I ruled out cardboard be cause it can dent and end up being useless. There's wax but it would probably not be strong enough for a 24mm x 4ft mandrel

 

[shockwaveriderz]

teflon will not work as a 24mm x 4ft long mandrel....I know I tried...I purchased some teflon rod from Mcmaster-Carr with the intention of getting it CNC machined down to specific dimensions..the cnc shop said its too soft a material.....the cnc shop suggested I use delrin as it also has a pretty low coefficient of friction.....

I would make a guess that the plastics also might be too soft at that length...

 

[GL-P]

teflon will not work as a 24mm x 4ft long mandrel....I know I tried...I purchased some teflon rod from Mcmaster-Carr with the intention of getting it CNC machined down to specific dimensions..the cnc shop said its too soft a material.....the cnc shop suggested I use delrin as it also has a pretty low coefficient of friction.....

Okay, McMaster-Carr does have some cheap delrin. I'll see what everyone else says.

 

[Kaycee]

Delrin from Mc Master-Carr.

Great sevice too

 

[edwardw]

What is the mandrel going to be used for? Is it a composite tube? I'd say check local plastic shops for material first. I've know I go there first because you can choose a nice and straight piece. If you are looking for something 24mm it might be easier to find some that is 15/16 and build it up. Machining something 4' long that is that diameter it can get wobbly turning it and it ends up not consistent. My best suggestion is to get something smaller and wrap it with mylar until you get to the diameter you want.

Edward

 

[KDRaven]

I use a 1" wood broom handle wraped with thin packing tape for macking motor mount tubes with but it is alittle bent in the middle of the 4' length to use the entire thing for a body tube, but it works great for motors.

just my .25 cents worth, you know inflation now days.

 

[Micromeister]

What type of mandrel do you use?

I've narrowed it down (or not) to these:

Steel-cheap, able to turn down to size
Aluminum-able to turn down to size
Polypropylene-epoxy doesn't stick well to it
Polyethylene-epoxy doesn't stick well to it
Delrin

I need to be able to accurately turn them down to 24mm OD for my motor.

Any suggestions? I ruled out cardboard be cause it can dent and end up being useless. There's wax but it would probably not be strong enough for a 24mm x 4ft mandrel

I've used delrin for a couple mandrel projects. One of the really nice properties is no mold release needed for FAI single or double layer glassed model bodies, just throw the whole thing in the freezer for awhile, the delrin contracts slightly and presto the Glassed body pop's right off. Second choice is aluminum "7000 series".
Hope this helps.

 

[m85476585]

To keep a plastic mandrel straight while machining it or using it, you can buy tubing (assuming it's available in roughly the size you need) instead of a rod and put a tight-fitting steel rod or tube down the center.

 

[kramer714]

steel hydraulic tubing, smooth, cheep, and accurate diameters.