I know all to well what your saying about a metal jaw vise and it marring up the axle shaft .
And I for one and like most have had the worst of luck with trying to cut a K -house groove in a pinewood derby axle head with the large loop type hack saw.
This year I'm trying to get away from showing my son.. my methods and/or ways of doing things that are not safe for him to do .. ( and that only adults can / should do.)
So I'm trying to find better ways that are more safe for him to do.. so that I can get him more involved with every step of making his own car..
Even if he wants the K-house groove's in his axles for tuning his Cub Scout outlaw car.
So on my way home I stopped in a Harbor Fright today.. for a smaller size Mini hack saw that was on close out.. and a smooth rubber jaw vise that was on sale for him to try.
https://www.harborfreight.com/2-34-in-a ... zYQAvD_BwE
If he has trouble with just using the vise and the mini hacksaw to cut a groove into the axle head.
My next thought is,, to take one of my (Older Derbyworx axle press's)
And to modify it by drilling out the head tapering end of the tool larger so that the axle head will set lower down into the press
and then using the seam in the middle of the two half's of the tool to guide the hack saw blade while cutting the groove into the axle head .
Clamping the axle in the Derbyworx axle press and then into a vise,, and then letting him go at it with the mini hack saw.
Then there is this screw slotting tool that iv seen posted on different pwd site topic for slotting axels.
However its made for Gun Smithing!
( I'm not advertising for this vender! just saying ... )
That he is the only vender that I know of.. to even offer a axle slotting tool.. in his tool line up for axle tuning .
https://www.turboderby.com/product-page ... roove-tool
