RoryMay

Slit and drift on the diamond

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I am attempting to slit and drift a square hole in 5/8" square bar. But this is not on the flat, yet the hole needs to be through on the diamond. The hole is 5/8" square as well and is also on the diamond.

I typically upset first, slit, drift, clean up and then run a final sized drift for my last pass. I am having issues getting the drift to go through it straight, as well as keep the bar on the diamond position. I attempted to upset and flatten a spot to start my drift but can not get the bar to stay in the position I need. Also tried the swedge block but it ended up forging the material on the outside when the drift was going through.

Any tips? Having difficulty pulling this off cleanly.

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I have seen it done where they made a couple of differrent V blocks to support on the diamond
The first was just a V block the second was more open and had a slit in it for the drift

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Just an idea, I have not tried it, but what about holding the work in the vise with V blocks and have the area you want to drift above the vise.

The work may bend a bit, maybe too much, may be worth a try though.

Caleb Ramsby

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thanks for the replies! I was also sent a picture of a tool of what Mark Aspery used to make one. Though the BP is interesting technique and is a punched hole and not a slit and drift. Trying to keep the integrity of the edge of square bar.

Defiantly have some more techniques to choose from. Thanks again


https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/418145_407878445893523_100000141134475_1698035_104090866_n.jpg

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I don't know that I can help at all.
I would slightly flatten the exact area of the hole to allow some traction to the slitter. Then use a v-block to slit to the center. Then use a v-block like the one you pictured that supports the bulge, to do the drifting. I would not upset first as that will prevent the metal from laying flat in the V-block and distort your bar.

Let us know how you do it and post some pics of the results when you get done!

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Its definitely not possible for most people, but I have seen a really SLICK way of doing this! I watched one shop that owned a water jet cutter stack bars in the machine propped up on the diamond and they slit many holes with the water jet. The holes were vary vary thin and perfectly cut. After all the holes were cut they heated the bars in a forge and drifted them in the normal fashion over the anvil and a bolster block. Because the holes were already cut the slitter and drift they used to do the final shaping left vary little distortion to the bar! I though it was a wonderful use of new technology. Sadly I do not have a water jet cutter so I am limited to day dreams on this one.

I guess if some one had a project that required a great number of these holes cut it is possible that they could have all the holes marked out and pre-cut by a company.

Sorry I am not more help but at least this is a fun idea!

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Otto Schmirler's book "Werk und Werkzeug des Kuntschmiedes" has a sketch of a fixture with a support block that moves aside as the chisel exits the work. IIRC, he also shows splitting from both sides so the work is not from one direction only, which helps balance the hole.

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Just my opinion. If I had the need, I might make an anvil ( bottom tool ) from some angle (with a pass through for the top tool ). This might have a place to either grip with vise grips or maybe just a tong ring affair. The slitter on the top ( this ALL in the guillotine tool ). Might be a good challenge. One way slit would be tough yes.

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Just for fun, I tried what I mentioned above. My general opionion is that I'll not be incorporating that design in anything anytime soon. LOL Actually it looked ok until I went square with the hole.

I used 5-inches of 1/2-inch square and slit and drift a .5-inch hole. The stock grew .25-inch.

I modified my V-block with a .75-inch hole, and also square up the curved inside corner of the angle iron that my v-notch is made out of. I chamfered the edges of the hole as well.

Here we have the v-block, the 1/2-inch square drift, the 1/2-inch round drift, and the opener.
DSC04333.jpg

The first thing I did was flatten a small area, front and back, over the horn.
DSC04336.jpg
DSC04335.jpg

I marked and punched using a v-shape punch.
DSC04341.jpg
DSC04342.jpg

After the opener.
DSC04343.jpg
DSC04344.jpg

After the .5-inch round drift.
DSC04346.jpg
DSC04345.jpg

After the .5-inch square drift.
DSC04347.jpg
DSC04348.jpg

The side view shows the distortion of the stock. The stock could be upset like Rory May mentioned, and this would compensate for the distortion, but we still run into the problem of how to support the stock with a bulge in the center of it.

I started by trying to use a short v-punch held in a pair of v-notch tongs. Well I hit a sour glancing blow which promptly sent the punch at great speed, through the window next to my forge. :(
DSC04350.jpg

Bummer!

It was fun trying it out. I'd be interested to see what other folks come up with.

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Hi Dave, Why drift it round?

When its slit knock it up to open the slot and then drift square. That way you maintain maximum thickness if the slot is the right length

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Hi Dave, Why drift it round?

When its slit knock it up to open the slot and then drift square. That way you maintain maximum thickness if the slot is the right length


+1...I drift square without going to round first - and vice versa. It's a waste of time, even if it worked...

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+1...I drift square without going to round first - and vice versa. It's a waste of time, even if it worked...

How is it a waste of time if it works?

If you are doing these you do need to tool up for them, a V for slitting, a V+shaped cavity for drifting and a top and bottom swage to tidy the job up.

It is also essential to have the correct sized slitting tool for the job

Dave nearly had it until he started to drift square then he appeared to stretch and deform the sides because of lack of support Edited by John B

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How is it a waste of time if it works?

If you are doing these you do need to tool up for them, a V for slitting, a V+shaped cavity for drifting and a swage to tidy the job up.


It's a waste to use 3 heats if 2 will do the trick, i.e., no reason to drift round if drifting square is all that's required. Obviously, it's not a waste if that's the only way to do it...

And such is the inefficiency of communicating on the internet...

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It's a waste to use 3 heats if 2 will do the trick, i.e., no reason to drift round if drifting square is all that's required. Obviously, it's not a waste if that's the only way to do it...

And such is the inefficiency of communicating on the internet...


Got you now, Thanks for the clarification.

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Hi Dave, Why drift it round?

When its slit knock it up to open the slot and then drift square. That way you maintain maximum thickness if the slot is the right length


right you are John. That was my suggestion and how I do any slit and drift. Slit then upset, then drift. It eases the force necessary to drift the stock and reduces the distortion.

Dave, if you wanted some ventilation at your forge couldn't you have opened the window?

Frosty The Lucky.

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Dave, For all your window replacement needs, just call my dad, your local and friendly Pella Window and Door Company Sales man. LOL

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Here's what I think on what you've done and how you could make it work better Dave. I believe that you'd have much improved results by using a wider slit punch (in this case trying for .5" square I would size the slit punch at approximately 7/8" wide... just under twice the length of the tenon sides). By doing so you'd have very little stretch when drifting the hole to fit the tenon... you'd mostly just open it up and square it out. The exact width of the slit punch could be adjusted after a few trial joints to be very accurate. I would NOT use the round drift because as you can see it leaves a gap on the sides of the mortise... curves where there should be flats. A slight upset prior to slot punching should get you a pretty well shaped joint by supplying the extra material needed to compensate for the slight stretching as the hole is drifted and the bit lost in punching. Lastly I would upset the punched hole a bit just before drifting so as to minimize distortion during that process. I wish I had time to try all this out myself but other projects are more pressing. I think the main improvement would come from widening the punched slot, thus shortening the bar length as the joint is formed but mostly keeping the bars profile intact.

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When I think about punching a bar, I think about the bar's stability. Flat bar is very stable - the surface doesn't distort much when the punch is driven home. Round bar is slightly less stable and square bar - held on the diamond is the least stable. That corner doesn't have enough mass to support the pressure of the punch.

So I upset the area to be punched a little and knock the corner down a bit to increase the landing area of my punch and therefore increase the available support.

For the diamond hole, my punch and my drift match in terms of width. A 1/2-inch square drift measures about 3/4-inch corner to corner. That's how long my slot punch is.

My drift is upset a little (to allow the hole to contract upon cooling) and is tapered across two corners.

The flat of the taper MUST be parallel to the corner to corner plane of the drift.

No need to open the hole (unless you want to). Support the stock in a bolster and drive the drift on through.

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As far as the support problem goes, now that you have an example of the finished product, you can make something to fit it perfectly. Weld some flat bar along the back of the support if necessary, and then cut out the clearance around the hole. Radius the cut edges and you won't have a problem marring the work as the unsupported section distorts. This worked for me doing 1" round holes in 1" square on the diamond. Came out perfect until I marked it up heading the tenons.

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