I have no good press on my workshop. I have been tempted to buy one of the cheap table top shop press thingys, but they are too small and too big at the same time.
I need something small, lightweight, easy to dismantle and store solution. I generally don't need very much grunt or use big parts though.
People have tendency to do a lot of compromises, but I'm having a lot of problem with universal tools that do nothing well.
My most immediate need is to broach some 6 mm and smaller keyseats and there is one inspiration:http://images.wdsltd.co.uk/7400/11/marlco-heavy-duty-two-speed-broaching-hand-presses-wds-6551
There is one of right size, but this is for pull broach:http://modelengineeringwebsite.com/Broach.html
I need about 350 mm of continuos stroke. I don't like to put any packing pieces and such to extend stroke.
I think I need about "1-2t" of force. 6 mm broach is quoted of 1000 kg and 8mm for 1700 kg.
I don't want it big I'm thinkking of max 150 mm dia parts between on two colums. Bigger ones must be boltted on the base or something.
1) Hydraulic, I have one hydraulic auto frame puller kit. I has a hand pump and 4t push cylinder with 125 mm stroke.
I have palans of using this as a small bearing press, haven't "found" small C-frame for it, probably need to fabricate one. At first it sounds good, but continuous stroke lengt is not enough. Therefore I would need another hydraulic cylinder and brocah movement would be pulsating because of the hand pump.
Is non continuos movement a problem for broaching and bearing assembly?
2) Arbort press. I found almost two meters long round bar that has module 1,5 tooth rack on it. Both ends are knackered and 100 mm of the rack is crap at the other end, but most of it looks usefull.
I did some fast calculation and it looks like this tooth module is way too small to transmit more than 400N of linear force. Way too litle. Am I off by factor of 1000 or something? Commecial arbor presses seem to use whole lot more coarse module.
That would also need a rachet mechanism or mighty big wheel. If I can't use this rack I sould buy all parts and then I'm not that thrilled.
Although it looks like this approach would produce small footprint and small storage space press.
3) Screw jack. Starts to look like best canditate. Trapezoidal threaded bar and nuts are not that expensive.
Push screw arragement looks simple and compact, but probably would need a pretty big diameter screw to keep it from buckling. Pull screw would probably be cheapest but lenght would grow and I would like to keep underside of the press unocupied from he junk. This would allow ocassional broaching of the bigger parts.
And I have two 0,55/0,75 KW worrm gear motors that has output speed of 100 and 140 rpm.
Very tempted to buy 1 metre trapezoudal thread bar, cut it half, couple two nuts together, but thread bar on pull arragemet and power them with a gear motor. 4-5 mm advance would give pretty decent speed and probably even enough force.
These gear motors have hollow secondary ID 25 mm with 8 mm key seat and gear has a reaction bar. This should make it pretty easy to mount and disassembe it between uses. I have another workshop application in mind and planning to switch motors between units.
Unfotunately gear motor bearings can't take axial force and secondary shaft hole is only 25 mm. That is a bit too small to use trough the gear thread bar and couple the nut into it. Would make it very simple.
I don't have any good experience on key seat broaching (other than I'm not going broach 6 or 8 mm key seat on lathe).
Which one of those approach would work best on push broach and why? I need to build the frame and bits anyways. I'm plannig of buying the push broaches, but I'm making the shimms and bushings as I need.