Talk to me about bench top lathes

[Sniper338]

I would say making expander mandrels 1 thou difference in each would be a challenge on any lathe. The difference between a warm mandrel and a cold mandrel might easily be .001.

True, didnt think of that..

 

[Dusty Stevens]

Making mandrels is a grinder operation seeing as how they need to be hardened and all. I get my expander pins for less than $5 on ebay and theyre perfect every time

 

[Sniper338]

Making mandrels is a grinder operation seeing as how they need to be hardened and all. I get my expander pins for less than $5 on ebay and theyre perfect every time

That reminded me of a thread a while back about somewhere to get pins for cheap... there was a website and all. Your remember that thread it was a good discussion about neck tension and using mandrels instead of bushings?

 

[Dusty Stevens]

Do a search for porter precision mandrel die. I get my pins from ebay

 

[McFred]

I would say making expander mandrels 1 thou difference in each would be a challenge on any lathe. The difference between a warm mandrel and a cold mandrel might easily be .001.

I respectfully disagree. It should not be difficult to hit a dimension within 0.001" for short distances. It's harder if you have to do it over a significant length. That's where the capabilities of the machine (and operator) start to reveal themselves. If for some reason you need that 4th decimal place in accuracy then you can get out the emery paper and the micrometers.

The difference in diameter of a .250" OD hot steel mandrel and a cold one will be virtually undetectable by mere hand inspection tools outside a climate controlled certified inspection room. Thermal coefficient of steel is 6.5*10^-6 per inch per degree F delta (or 0.00016" for a 100˚ temperature delta for .250" dowel). Granted the difference is more pronounced for larger parts in climates with wild temperature differences.

2¢

Just keep in mind...that little stuff will turn into big stuff. Get a machine you can do barrels on and the same machine will be fully capable making small parts...

Ridgeway is correct about this, I can't say I've ever heard someone saying that a lathe is too large. Like gunsafes and garages, whatever you think will be enough, double the size. I know for what I usually do what I have is overkill, but it's nice to know that if I need it, the capacity's there:

17x80 gap bed, gear head lathe. 40-1800rpm + VFD speed control