V Block Material

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Harold_V
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Post by Harold_V » Wed Apr 08, 2009 2:59 am

seal killer wrote:Can I heat treat these little pieces with a MAPI torch or my tiny acetylene rig? If so, what is the process? Dull red and then dunk'em?
Get some HT 4140 or 4142 instead. It's already hardened adequately for the purpose (28-32 Rc), but you can still machine it reasonably well.

If you elect to heat treat chrome moly, it's always a good idea to give it a proper draw in a furnace. That stabilizes the material so it isn't subject to shock. You're better served to buy it already heat treated. It will serve you perfectly well.

This stuff won't be like aluminum----it's very sensitive to over speed (using HSS tools), so use care when selecting spindle speeds. It's tough and cuts short tool life, but it's an excellent choice for parts under stress.

Harold

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seal killer
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Post by seal killer » Wed Apr 08, 2009 7:25 am

Harold--

HT 4140 or 4142 it is, then!

I have a LOT of solid carbide end mills that were freebies. Some have never been used. I think I even have a couple of solid carbide, 4-flute, 1/2" end mills.

Thanks.

--Bill
ps I'll study MH and try to cut it at the correct rate.
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seal killer
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Post by seal killer » Thu Apr 30, 2009 2:42 pm

All--

Some time back, I created this topic to find out what kind of steel I should use for a clamp strap on a V-block my brother-in-law gave me. I already have a couple of this type of V-block, but I thought making the clamp might teach me something.

4140 or 4142 was suggested and that is what I asked my local vendor for. He either had none or had none from which cutting a chunk out made sense. I think it was the former. Anyway, he had plenty of 1018, so I bought an entire SIXTEEN DOLLARS worth.

I made the clamp . . . three times. It wasn't that the machining was difficult; I just cut my spindle speed down to about a third of the RPM I use on aluminum and experimented with the 1018 while squaring the retangular block. Soon, I had the nice tan chips I have heard so much about.

What I DID find difficult was extracting the correct dimensions from the V-block for the V-block clamp strap. The other difficult thing for me was trying to make one exactly along the lines of the ones I already had . . . they are designed differently.

Anyway, I finally got'er done. Now, the strap pictured below has a rather fine point (relatively speaking) on it and would only work with small diameter round stock. I will make another one just like it and then two more sets with wider flats to hold larger diameter stock.

Then, of course, there is the other side which is larger. I'll need to make sets of V-block clamp straps for it, as well.

I have no idea how 1018 will work for this purpose. I will probably only use it on aluminum, so I GUESS it will at least work. Additionally, those SHCS are "place holders", only. I replaced them with longer ones that were "hardened - heat treated" from my local farm supply store that are not threaded all the way to the bottom of the head. I don't know if they are strong enough. (I certainly won't clamp my aluminum round stock as much as I would steel. Maybe I should check McMaster-Carr or someone for some Grade 5 or Grade 8 bolts?)

Thanks for your help and sorry if I misled anyone about the exact type of clamp I wanted to make.

Image

--Bill
ps That is my new Albrecht Keyless Chuck with integral R8 adapter in the mill. Previously, on another thread, I claimed it was a 0" - 0.5" chuck. It is not. It is a 1/32" to 0.5" chuck. (I couldn't hold anything smaller than 1/8" with the chuck that came with the mill. The Albrecht is a vast improvement.)
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Harold_V
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Post by Harold_V » Fri May 01, 2009 12:17 am

Your material choice is fine, although it will have a tendency to mush when (if) you tighten the clamps on hard objects.

I must admit, I had a totally different kind of clamp in mind----more in keeping with the type that come with the Starrett V blocks I own. Mild steel would not have been a very good choice for that design.

Nice job, Bill.

Harold

Jay, Idaho
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Post by Jay, Idaho » Fri May 01, 2009 9:09 am

Nice job. If you are going to leave the clamp soft, you might want to put flat washers under the screw heads. Hardened washers would be nice but any washer, even brass, will protect your clamp.

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seal killer
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Post by seal killer » Fri May 01, 2009 9:49 am

Jay and Harold--

Thank you.

Jay, flat washers it will be!

--Bill
You are what you write.

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