My Homemade Edge Clamps
I have seen tons of articles and posts on various edge clamps. It seem like Mitee-Bite is the most popular manufacturer, and for good reason, their clamps have some serious holding power. I have been working on some fixture plate designs to hold 10-20 rectangular parts that require surfacing, chamfering, and engraving. After doing extensive research, I couldn't find a clamp that would hold a .125" part, and still allow me to chamfer around the perimeter.
Since my expertise is in CAD, I decided I would design my own. While looking for inspiration, I discovered that all Mitee-Bite cad files are available on their website. I downloaded and imported their Solidworks files, and came up with a design very similar to their pitbull clamp, only smaller.
I was able to machine them in three operations. The steel cost me around $6.50 and from start to finish it took me around 4 hours. (including design)
As you can see the overall design is almost the same, I just changed a few dimensions to increase the throw of the clamp, extend the depth of the clamp slot, and allow me to grab a lower portion of my part.
The tooling plate I am working on is 12" X 14", 1" thick, and will hold 12-16 of the parts you see in the pictures.
Although I used 3 edge clamps in my sample (mini) plate, they really only require one clamp per part.
Seeing that pitbull clamps start at $80 ish per pack, I think I'm just going to continue to make my own, and save up for a pony
Hope you guys enjoy.
Last edited by Blackdiamond; 08-11-2012 at 07:00 PM.
I do a valve cover insert for a local company
my makeshift holder plate was a recess with a machined back edge as a referance
I would spring clamp the insert in place then hot melt glue the perimiter to hold during the logo engraving
I think I'll spend the time and make a set like yours
While I applaud your ingenuity in building these I think it would have been a lot cheaper to just buy them. Material's not much but at a shop rate of around $75 per hour your six clamps cost you about $50 each. At $80-$90 per six-pack the Mitee-Bites are quite a bit less...
make sure you make a good set of jaws to hold them. Since the profile op requires you to stand them up, your setup needs to be rigid. If you get chatter marks on the leading edge of the clamp (the part that holds against your work) then your in trouble. That's the only issue with small parts, your tolerances are very tight. Im planning on making some .25" an .5" edge clamps tomorrow. Should be much easier.
You might be right. But I machined specific jaws for the parts, and a fixture to make more in the future. I ran 10 sets (of 6) for a total of 60 in an hour. If you have multiple fixture plates and multiple machines, it would save quite a bit of money. Especially for those who make 50-100 part fixtures. A grand here and there adds up. However, I guess I determine my own hourly rate
its not always about the calculated cost/part
there needs to be a few "I made this" in everybodys shop, evan if the calculator says its cheaper to buy
Never found any info on DIY edge clamps. Maybe I'm wrong, but seems like everyone thinks they are too complicated to make... Honestly wasn't too bad.
You made them from 1018? Get good at making them because they will not last very long.
Originally Posted by Blackdiamond
I also applaud your efforts of making your own tooling, but if you are going to make them again, make them last by selecting a better material.
I read my receipt wrong it was 1074..... . I mainly machine stainless, and al. What steels work the best for this type of project? Is it possible to DIY heat treat? Now that I have the program and setup done I can make a ton more.
Nice job on these clamps. I too would suggest using tool steel rather than 1018. 01 tool steel would be my choice for them if I did not have a heat treat oven. I think it would machine nicer than 1018 though yours look very good. O-1 would be a cinch to harden and temper with just a MAPP gas torch and some oil. It would take a very short time to bring them to red heat and quench them. After that the whole batch could go into your oven at 425 or 450 to temper them. If you have access to a heat treat oven A2 would be what I would use. It too would machine more nicely. You could put a bunch of them in stainless foil and treat them all at once. Either way you would have a very durable clamp that it would be hard to wear out in frequent daily use.
It would also be possible to case harden the 1018. Seems like that would be a nuisance in comparison to making them out of tool steel in the first place.
I have been contemplating such a project for a while now. Your success is encouraging. Kudos.
I was typing while you were typing...
Most grippers are tool steel and heat treated to around RC60. Some have carbide inserts. Carr Lane uses M2 tool steel.
My experience with heat treating this kind of thing is that when you take the steel up to the temp required before quenching, the sharp details of the knife edge are burned away. That means that the knife edge has to be form ground after heat treating. That is where most of the cost is.
If you are just working in aluminum, the clamps will probably last a long time.
I very rarely work with "billet" type materials. Castings very way too much to use this kind of clamp. The clamping range is just too small.
Thanks for the info. Most of the parts I machine are stainless. Holding them isn't too tough unless they are tall or an awkward shape. Considering that I can make many more, if they wear out quick, so be it. I guess I need to experiment with different steels and see if there is a huge difference in this situation. I know as i get into making bigger ones, I'll need a stronger material.
Pretty nice job on the clamps. If you decide to have a go at these again out of tool steel & need them hardened, shoot me a PM if you like. I imagine I can accommodate.
Originally Posted by ewlsey
Actually I think the forms shown in this design are not all that knife-like and in the case of O-1 I have heat treated with a torch this type of item many many times with minimal (not really discernable) decarb of the edge. Part of the lack of trouble here would be due to the only 10 or 15 seconds of holding the heat at cherry red. (Yes, I have read countless times about longer soak times but I will positively guarantee you that is not needed) In situations where decarb is a concern--like a ground cutting tool-- I apply an anti-scale compound like the one made by Brownell's. That completely prevents decarb or burning and is simple to apply and clean up. I very much doubt that would be needed for these parts. First try just simple torch heat treating O-1. If decarb is a problem use the Brownell's Anti Scale.
All this science talk makes me happy I machine stainless hahah.... Except it's just a bit more expensive. There are tons of threads on DIY heat treat. Everyone has their own methods it seems like.
A pre-heat treated 4130 material is a great choice for short to medium run clamps. It is readily available, it machines with relative ease, its tough, and it bends rather than fracturing.
You will wear out the heel rest for your clamps long before you wear out the first set of clamps from PHT 4130.
Use a magnet to determine when you've reached your critical temperature. God loves blacksmiths. The steel will no longer be magnetic when you are at the right level of cherry-red. make yourself a little wire hook, and heat them on the hook, then dunk in oil. Motor oil works, but don't breath the smoke if you can help it. Deep fryer oil from a fried chiken joint smells like heaven when quenching. Both will produce a little bit of flame during your dunking process.
If you want to see if you quenched it right, try to file one of the parts at this point. The file should just skip right across the part without cutting. Put them in the oven for an hour. Use your own Google-fu to determine the temperature. For knives you shoot for a straw color... you may choose to stay harder for your clamping application.
Now that I've rambled on about that, I'm not sure i understand how your clamps work. Is the bottom surface curved, causing it to rock forward and down?
These are by no means my design. Its just my spin on a Mitee-Bite Pitbull clamp. they do not make one small enough for the extremely low profile of these parts, so I decided to make my own. There is a radius on the back side of the part. The bottom is angled, so when the back radius wedges against the back of the slot wall, it forces the leading edge of the clamp against the part. Since the leading edge is a flat edge (not knife style) the clamps will no longer tighten down once they are flush against the edge of the part.
I don't even know if what I said made sense lol but it kinda did to me.
As long as second-guesses are allowed, I would opt for 4140 HT (32ish HRc). Tough, but won't trash a carbide end mill if you happen to get on one accidently. It happens!
Yay for multiple part set-up shop made tooling, nice job !
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