Tiger 7th April 2015, 11:26 AM Mucking around on the weekend and experimenting with some holdfasts, it would have been very handy being able to bend some rod that was almost 3/4 inch in diameter. Had access to a pipe bender years ago and that was great for metal tubing and pipes but don't have it anymore. Can you rig up some equipment for a one-off job like this? Don't really want to go down the pipe bender purchase route as would not get value out of it. I'm assuming I must use some heat to help the bend and it's mild steel.
BobL 7th April 2015, 11:48 AM Making steel hold fasts is not just a matter of bending a piece of steel rod. The end that makes contact with the work must be appropriately flattened which requires a significant source of heat like a forge. I have seen holdfasts made by hand by just grinding a sloped flat surface onto the end of a rod but the surface area is too small and it marks the work so a protective piece needs to be used but even then sometimes the contact area is not large enough so the work moves.
sacc51 7th April 2015, 07:39 PM If you heat up the rod, stick it in the vice, slide a piece of thick walled tube (overtube) over the rod and pull it gives a pretty good bend without the straights bowing. The end of the over tube needs to be around the thickness of the material away from the vice or you will get marks on the rod. You can do the same without heat with a thicker and longer overtube. If you don't want such a tight bend, use a dog or round bending jig in the vice. The inner diameter of the overtube needs to be as close to the rod diameter as possible otherwise the straights will bow.
Tiger 8th April 2015, 12:37 PM Thanks guys, I don't use holdfasts much but a couple of occasions lately they would have come in useful, not critical that I can bend them as I could always weld a flat onto the holdfast stem, just thought that I could save a bit of time and see whether bending the rod was an option.
Ben Dono 11th April 2015, 07:56 AM Post up some pics when your done!
Like the other post said, try a cheater bar first.
When ever I need to bend up something complicated that's too thick to bend cold, I usually make shallow cuts with a thin cutoff wheel to weaken it. I just weld it up after to strengthen it again.
I don't have an oxy so if I'm hot bending something, I just get a little creative with light weight fire bricks and use a big propane torch. Just the big primus head in the handyman kit.
Mapp gas is even better but bottle gas is cheap.
You can find refactory bricks from pottery supply shops.
Perlite is even cheaper (garden supply) but it's loose and not good for forming walls. It does not last very long either but it works.
Tiger 13th April 2015, 11:22 AM Thanks Ben, I've been looking at options to ox-acetylene so your info is timely. I ended up welding some flat bar to some rod for my holdfast. It holds well but I'd like it to release a little easier. Used mild steel, 10 mm flat bar and 19 mm rod, the 10 mm is overkill but I didn't have anything thinner, will put up a pic later.
Tiger 14th April 2015, 10:49 AM Here's what I came up with. Holds well, would like it to release a little easier though. Flat bar just welded to rod, didn't have any suitable pipe to bend the rod.
Ben Dono 14th April 2015, 10:56 AM Nice one! Looks like it will do the job quite well. I think I will knock up a few of those.
Look on the bright side, it's better than saying ' I wish it would hold on a little tighter'
I did see a video a while back where the woodworker pulled up on the hold down and smacked down on the bench right next to rod with a wood mallet. The vibration let it come loose....I guess every clamp,bench, hole etc will be different.
Maybe have a little over hang on the back so you can tap it up with a hammer or use the claw to pry it up if it's too close to the bench!
BobL 14th April 2015, 11:49 AM . . . would like it to release a little easier though. Flat bar just welded to rod, didn't have any suitable pipe to bend the rod.
Good effort.
To help it release they need more of a curved top rather than a hard right angle,
Tiger 14th April 2015, 12:04 PM Good effort.
To help it release they need more of a curved top rather than a hard right angle,
Thanks Bob but how does that help?
Ben Dono 15th April 2015, 11:41 AM You got me thinking again Bob! I would have assumed the friction points in the hole would have been the same on a curved or flat hold down? Maybe it's the extra length in the curve that allows for some more spring?
I like the simplicity of tigers clamps though. Every tool you have is going to perform a little differently than someone else's. I think I would just get use to the simpler to make option and play around with some ways of releasing it. Depends on what tools you normally have on your work bench I guess.
Hey tiger, what is your bench made out of and how thick is the top?
Tiger 15th April 2015, 12:25 PM Hi again Ben,
My workbench top is approx. 35mm made with a combination of Tas Oak and Pine, basically whatever had lying around. I've got storage underneath so had to make my own holdfasts as the bought ones were too long, also I wasn't sure that the commercial ones were going to work in a narrow width bench like mine but so far so good. The 10 mm bar is probably too thick and reduces the springing ability, if I were to make another one, I'd use something thinner. I think Bob's suggestion may be correct about the curved top, you have more surface area to hit it from behind rather than my design.
BobL 15th April 2015, 12:27 PM I think Bob's suggestion may be correct about the curved top, you have more surface area to hit it from behind rather than my design.
:2tsup:
sacc51 15th April 2015, 05:07 PM These are my holdfasts. I don't use them often, but spurred on by this thread I dug them out and cleaned them up. I’ve been meaning to convert them to floating feet for while, so this morning I converted one and gave it a coat of paint. They are made from 22mm x 2mm tube with a 25mm x 5mm flat on the top. The flat should probably be a bit thicker but that's all I had at the time. They haven't bent yet so perhaps 5mm is OK, normally I hammer them with my hand so that's probably why.
Tiger 15th April 2015, 05:59 PM Nice design Sacc.
.RC. 16th April 2015, 10:50 AM Thanks Ben, I've been looking at options to ox-acetylene so your info is timely.
When I was at high school in metal work the school had a LPG setup where the air was supplied by an air compressor...
If you really want some heat I once made a diesel air torch, and this was before I had any machine tools..... It would melt aluminium and roared like a rocket..
Ben Dono 17th April 2015, 09:42 AM Now you have gone and done it RC! Diesel torch! Can you put up a bit more info mate?
BobL 17th April 2015, 10:11 AM When I was at high school in metal work the school had a LPG setup where the air was supplied by an air compressor... .
My Forge is mains gas turbo charged with a vacuum cleaner. Once it has warmed up it can get a steel rod to 1200º in about 5 minutes.
Details here http://www.woodworkforums.com/showthread.php?t=168547
It's a relatively complicated build because I'm using it inside. If it was being used outside it could be simpler.
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