Making some screw less vise hold downs

[WobblyHand]

So, finally got around to completing a drawing for me to machine some hold downs for my new screw less vise that I just received. For some reason I couldn't visualize what I wanted to do. So I have a dxf drawing. Or pdf. The inspiration for the hold down can be found on the Little Machine Shop website. They call it a Z hold down.

I'd like to make 6 of them. My plan is to start with a piece of 1.5 x 0.75 low carbon stock, cut it to 5.25" and mill out the basic profile except for the little 0.06 x 0.06 feature. That's just to make it easier to hold in the vise. Then drill the holes. I have no idea how I can get the 45 degree cut at the moment, but it's only for aesthetics. If I had more 'stuff' that would be easier. No matter. I'll have to make some sort of spacer, just so the piece can be clamped in the vise. At the end, I was hoping to cut off the finished pieces one by one with a slitting saw. Is this an ok plan? Any things to watch out for?

Your guidance sought. This is the part where beginners mess up, the order of operations. They (me) also often don't realize when there's a vastly easier way to do things.

 

[Mitch Alsup]

I see little advantage to the z-profile over a profile where the side the screw goes through is level with the part that is pushing down on the vise.
That is only cut out the part that grabs the vise and leave the rest square--unless you are fighting some kind of clearance issue.

 

[WobblyHand]

Thanks for your observation. Not knowing any better, I attempted to roughly duplicate the profile. At least with the vise I have, the flat will not be level, actually it will slightly tilt upwards towards the vise. Does this matter? Haven't cut any thing yet, so all's fair.

 

[Mini Cooper S]

I agree with Mitch and would advise to also add a radius inside the hook that clamps the vise for strength. That sharp corner is a stress riser for cracking.
Also, make the clamp longer, the short distance from the end to the hole will cause all the clamping pressure to it clamp the table with the vise acting as a step block.

Richard

 

[WobblyHand]

I agree with Mitch and would advise to also add a radius inside the hook that clamps the vise for strength. That sharp corner is a stress riser for cracking.

Richard

I think I have an end mill that's got a slight radius to it at the tips. Hope I have something close. I don't have that big of a collection.

I see little advantage to the z-profile over a profile where the side the screw goes through is level with the part that is pushing down on the vise.
That is only cut out the part that grabs the vise and leave the rest square--unless you are fighting some kind of clearance issue.

Took me a couple of readings to have this sink in. I can skip the nubbin. Less machining.

 

[WobblyHand]

Is something like a 0.020" radius ok?

 

[Mini Cooper S]

Is something like a 0.020" radius ok?

Better than nothing but I would probably go about 1/16". The bigger the better because it is adding strength to the part and distributing the stress to a larger area. Did you catch the editing that I did to my other post?
Richard

 

[Mitch Alsup]

Took me a couple of readings to have this sink in. I can skip the nubbin. Less machining.

'Zactly !

 

[higgite]

Thanks for your observation. Not knowing any better, I attempted to roughly duplicate the profile. At least with the vise I have, the flat will not be level, actually it will slightly tilt upwards towards the vise. Does this matter? Haven't cut any thing yet, so all's fair.

Took me a couple of readings to have this sink in. I can skip the nubbin. Less machining.

Wobbly, I don’t think you want the clamps to be tilting upward. When you tighten them, they will tend to push the vise sideways out of tram. Conventional wisdom is to have a clamp tilting slightly downward at the contact point so that it clamps without pushing or pulling. That is actually the purpose of the “nubbin” on the underside of the clamp body. Otherwise, I like your plan.

Tom

 

[WobblyHand]

@higgite yes, for clamping I do want the flat tilting downwards. That's the way I use regular hold downs on the mill. Well, time for version 2! At least this time, I won't have forgotten how to use the CAD program. It doesn't take very long before CRS sets in. That's not cold rolled steel, by the way. I'll make the pieces taller. C'est la vie.