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View Full Version : Making my own bender dies ?

ElPasoEric
03-21-2006, 05:55 AM
OK, first off, I have never used a metal lathe so please dont get all pissy if I don't have a clue what I am doing, lol.

I have a few billets of mild steel about 8x8 and about 2 inches thick and I wanted to make a couple of bender dies with them if possible. They are square and freaking heavy. How can I cut them into circles? I was thinking of using a cutoff wheel on an angle grinder and making them about as round as I can and then chucking them up in my lathe to round them out, it this a good idea? Do I need to eliminate all of the squared points on it before I turn it down or should I just very, very slowly put the cutter to it and then start clearing it back and forth?

Now for the fun part, I was planning on setting the perfectly round die on its side atop a rotary table on the tool rest and then chucking up a 1" ball end mill in the lathe and trying to cut the halfround into the die like this, will it work? My lathe only goes down to 120RPM and I have no clue what speed to use for the ball mill. I was also thinking of doing this like flat50 did with his bedomatic by laminating the dies, but make the lams like 1/4" and then just make a finished radius with the ball mill. I know they will need some kind of hardening, but I think I will deal with that later, or just buy a die if I plan on using anything more than .095.

Anyone think I am going through way too much trouble for my own dies? I just want to do it this way because I feel if I can get it right then I can stock myself up with a dozen dies for the price of 3 at jd2 price. I got the billets for free from the local steel yard when I bought all my channel and angle for my trailer and he said he will keep any more that he happens of have lying around if he finds more.

Also, YES, I do have more time than money. I am self employed as a roofer and I have some weeks where there is just no work so spending 20hours+ on making a single die set is not too big of an issue, as I have given it some thought already.
bignissan
03-21-2006, 06:12 AM
well, if you have more time than money, give it a shot. Sounds like you've got the material already. Go try it and see if it works.
ElPasoEric
03-21-2006, 06:15 AM
I mean I am planning on trying it, no doubt, but the thing is I do not want to kill the lathe (It's a loner from a friends grandfater who said we would have more use for it than he but he didn't "give" it to use, just loaned it) so I want more ideas on speeds and how round the billet need to be before I start it in the lathe.
ElPasoEric
03-21-2006, 06:25 AM
Basically what I want to know first is how do I "round off" the billet' Here is an mage of how I planned on doing it but does it need more rounding before I chuck it up?

http://ericshandyman.com/images/proposedcuts.jpg
cheaprides
03-21-2006, 06:47 AM
there are formulas for this to get rpm and feed rate. do a search for this stuff it is out there. but if i were you i would just spend the money on a book so you get all kind of information that you may someday use.

have fun with getting that inside radius by hand. you might want to try to make your own tool bit for this.

i think most machinists would just buy the die and spend 4 hours extra in the shop making something for someone else.
ElPasoEric
03-21-2006, 06:51 AM
there are formulas for this to get rpm and feed rate. do a search for this stuff it is out there. but if i were you i would just spend the money on a book so you get all kind of information that you may someday use.

have fun with getting that inside radius by hand. you might want to try to make your own tool bit for this.

I am not making the raius purely by hand, I was planning on chucking up the ball mill and then just running it in to the billet .5" and do the folower basically the same way. To make the die I have a decent rotary table that seems real tight so think it will be pretty good.


i think most machinists would just buy the die and spend 4 hours extra in the shop making something for someone else.

If I were a machinist I would have already have the die, but as I am not and don't really feel confident in making anything for anyone else yet I want to try it like this.
jeepnmatt
03-21-2006, 07:50 AM
it may be worth scrapping the steel that you have and buying a couple of round plate "burn-outs". most steel places have flame cutting capabilities. have them cut out some circles from plate thate are larger than what you need, maybe with a hole in the center (for chucking).

or, get an acetylene torch and hack your squares into circles.
ElPasoEric
03-21-2006, 08:13 AM
I also thought of doing it with a torch, but that means I gotta go all the way back to the welding shop to get my oxy exchanged, but I gotta do it someday I suppose.
fivetenben
03-21-2006, 08:40 AM
google radius attachment. Its just a little dohicky that lets you do concave and convex shapes on a manual lathe. should be able to build a simple version yourself without too much trouble.
bignissan
03-21-2006, 08:41 AM
yup...cut it with a torch, then grind with an angle grinder to get close...much less machining time.
TLCObsession
03-21-2006, 11:55 AM
How are you going to do the follower?
ElPasoEric
03-21-2006, 10:28 PM
How are you going to do the follower?

I was planning on cutting a chunk down to a nice size and the using a vise to put it on the tool post table and the moving it from side to side with the turn screw while milling with the ball mill. Hope that made sense.
Psi_man
03-22-2006, 04:09 AM
I just finished machining two 1.75 dies… Its not worth the time for the price you can buy them.. I probably got 30 to 45 hours in machining them and I did it in CNC. But it might be a fun project if you aren’t waiting for them to finish another project.

I had some 13 diameter By 3 thick plate, milled both side flat. I turned them in a big 30hp akira seike cnc lathe. The chuck wasn’t big enough the grab the plate (and the plate was far from round) so I bolted it directly to the face of the chuck, then turned the profile

The follower block I roughed out as much as possible with a 1.25 and .50 endmill and made two passes with a 1.75 ballmill at 170 rpm and about .5” inches per minute, It took a lot of power to make those passes… 30% spindle load of a 15hp or 20hp mill

How big is your lathe? Hp? and what’s the swing??
ElPasoEric
03-23-2006, 04:17 AM
OK, so after about 9 hours in the shop watching the lathe, it became apparent to me that I need more HP. It was a little like watching paint dry, but having to watch it continuously. I got one almost done set of 1" 6.5CLR dies, but I think for anything bigger I am going to have to order them. I guess I can finish the one die and move on the making the bender though.