Shop Made Tools

[Bob Engelhardt]

Nice job on that.
A question though. It seems like all the material past the pin is not necessary as the pin carries the load. I believe it also may work a little better if the pin was farther out along the curve towards the tip. Where the pin is now I would think that maybe the pin gets levered out of the hole. If it was farther out the strap would wrap down on the nut holding the pin into the hole.

Then again I could be completely wrong!

I think that you are completely right. One could argue that the force on the pin is always perpendicular to it and the angular position doesn't matter. But if you think about the range of possible positions, it's clear that the further away, the better. So, if the pin were only 10 degrees "up" on the curved arm, it would clearly slip out. As the angle increases, the tendency to slip decreases. 90 is clearly much better than 10, and might be fine, depending upon the fit. But 180 is much better still and is unlikely to slip unless there is a lot of taper to the hole-pin fit. Even then it would require that the arm flex and not just be pushed away.

Bob

[jdedmon91]

I think that you are completely right. One could argue that the force on the pin is always perpendicular to it and the angular position doesn't matter. But if you think about the range of possible positions, it's clear that the further away, the better. So, if the pin were only 10 degrees "up" on the curved arm, it would clearly slip out. As the angle increases, the tendency to slip decreases. 90 is clearly much better than 10, and might be fine, depending upon the fit. But 180 is much better still and is unlikely to slip unless there is a lot of taper to the hole-pin fit. Even then it would require that the arm flex and not just be pushed away.

Bob

I did something similar for my bench top mill. Instead of bending the bar I bored out a piece of steel cut it in half put the pin in and tacked it with weld and made a handle for it. Worked well



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[rcaffin]

I thought that having that much wrap 'after' the pin just made it so much easier to fit the spanner to the collet nut. So much easier to use.

Cheers
Roger

[ezduzit]

...180 is much better still and is unlikely to slip...

180* would be impossible to engage or disengage the pin as the opposing feature would prevent it.

[Bob Engelhardt]

180* would be impossible to engage or disengage the pin as the opposing feature would prevent it.

Not at all ... the pin goes in first and the handle swings down. All of mine are the 180 degree variety & work fine.

[GNM109]

Deleted.

[_Paul_]

Indexable Rear Parting Toolpost for Boxford Model "A" Lathe

I like my HSS rear parting toolpost for my Boxford lathe but being HSS it really doesn't like some harder materials, so some time ago I bought a 3mm indexable parting blade and some tips and today finally made a toolpost to carry it, more rigid than the HSS post and seems to work well so far.









Paul

[ezduzit]

No pics.

[bborr01]

I like my HSS rear parting toolpost for my Boxford lathe but being HSS it really doesn't like some harder materials, so some time ago I bought a 3mm indexable parting blade and some tips and today finally made a toolpost to carry it, more rigid than the HSS post and seems to work well so far.









Paul

One question: Why mount it on the rear instead of like most people do?

Brian

[ezduzit]

Mounting on the rear eliminates the chatter and associated blade breakage that can occur when the cross slide lifts due to clearances.

[bborr01]

Mounting on the rear eliminates the chatter and associated blade breakage that can occur when the cross slide lifts due to clearances.

The cross slide shouldn't lift when the parting tool is in front near the operator. Conversely, the parting tool will lift the carriage when it is in the rear.

Brian

[Baz]

It is sort of the other way around. In front it can dig in, at rear it can lift to get out of trouble.

[ezduzit]

It is because, when mounted on the front, there is overhang.

[plunger]

Isnt also convenient to have it at the back because now you dont have to change tools. Its there permanently. I was always told an upside down parting tool chatters less. The swarf also falls out due to gravity.Is there truth in the upside down theory.?

[Davidhcnc]

Isnt also convenient to have it at the back because now you dont have to change tools. Its there permanently. I was always told an upside down parting tool chatters less. The swarf also falls out due to gravity.Is there truth in the upside down theory.?

Yes, We could talk about it all day. Try it and see the difference.