dangerousamateur Posted June 24, 2017 Posted June 24, 2017 I have tested a 2 ton arbor press from a pyro friend and put a PTF gauge under it.Pulling with al my strength I could get some 1,3tons of force. Without any cheater bar. Did you ever try what force your arbor presses could achieve in reality?
lloyd Posted June 24, 2017 Posted June 24, 2017 Yeah... they're all 'short' on what a normal person can do. The "ton rating" is the maximum force they're designed to withstand, NOT the force you can apply with the handle. A really heavy and really strong person might be able to exert the full force -- but being Chinese 'crap', I'd be suspect of their ability to actually withstand their marked ratings. I used to think that the force-rating was designed to represent what a 'normal' person (say 180lb) could exert literally "hanging" on the bitter-end of the handle -- but that's not the case. I was told that by a US vendor of the Chinese goods, and believed it for some time, until I actually put a P2F gauge under the thing and checked. Lloyd
dangerousamateur Posted June 25, 2017 Author Posted June 25, 2017 Well, I know there cannot be a definitive answer for that, but would you trust a rather cheap 2ton model to withstand that 1,3tons safely for a reasonable using time? And if it fails, whre whould you expect it to fail? The gearing? 1
lloyd Posted June 25, 2017 Posted June 25, 2017 The way I use them, I'd expect the frame to crack. That's because on the ones I use "near their limit", I've added air-assist to get the pressure up, without having to crank so hard on the handle. I have to be honest, and say that I've never seen (even a cheap Chinese) one fail. I have, though, cut the frames on a couple, and the cast alloy is really 'cheesy' stuff! Lloyd 1
dangerousamateur Posted June 25, 2017 Author Posted June 25, 2017 Lots of air bubbles hugh? OK, if they crack, then they crack... the smaller ones ore quite cheap and the hobby isnt.Thank you Lloyd.
OldMarine Posted June 26, 2017 Posted June 26, 2017 Just checked my 2 ton arbor press and with my fat ass swinging on the handle I got right at 2500 psi on my PTOF. I could use a longer handle but that is fine for what I use it for. It'll press ¾" rockets and 4x4 star plates just fine.
DavidF Posted June 26, 2017 Posted June 26, 2017 I generally use my cheap 1 ton arbor press at around 1500 on the PtoF. I use a click-type torque wrench to do my pressing after I set it to the desired value using the PtoF gauge. The torque wrench handle is considerably longer than the handle that comes with the press. Mine has hit 1500 to 2000 pounds of force a few thousand times by now. The worst thing that I have seen happen is that the retaining ring on the left can come loose. Then the gear can move to the right and the teeth come out of alignment with the teeth on the ram. Putting excessive force on the handle with this misalignment will damage the gear teeth.
dangerousamateur Posted June 29, 2017 Author Posted June 29, 2017 Your gauges are obviously 1inch, right?
lloyd Posted June 29, 2017 Posted June 29, 2017 (edited) Danger,It doesn't matter what the area of the ram is. Calculation may be done to examine what the actual pressure was! Area is area, regardless of size. When I have a 'purely arbitrary' gauge on a 'purely arbitrary' P2F piston, I simply overlay (or mark with a Magic Marker) what the REAL pressures are on the gauge! <grin> Lloyd Edited June 29, 2017 by lloyd
Mumbles Posted June 29, 2017 Posted June 29, 2017 But yes, most P2F gauges that you can buy from a pyro tool maker have a 1 square inch piston on them. Wolter and Caleb's do at least. I thought Ben Smith did as well, but when I just checked it doesn't appear that way.
calebkessinger Posted June 30, 2017 Posted June 30, 2017 You can get to the rating of your arbor press with it bolted down and an extra foot of cheater bar.. Going over the rating seems to bend the circular gears. ( I have a photo of mine somewhere ) I've taken my half ton press to 3000 lbs on my power to force gauge.. - hence the twisting of the gears- The larger 1 ton and up have a bigger gear setup that is harder to pull needed more cheater to get to max pressure easily. Lots of folks have gotten their larger 3 ton presses and only been able to get 1000 to 1500 lbs without bolting them down and using a cheater bar. I make standard power to force gauges, and also "double power" gauges that read half of what you are getting ( the cylinder is 2sq. in.) those are better for full size star plates.
dangerousamateur Posted July 1, 2017 Author Posted July 1, 2017 Danger,It doesn't matter what the area of the ram isI want to measure the force my press exerts on the target. The PTF gauge gives me a pressure value, so I need to know the pistons diameter. Or whats my mistake? Reagrding bolting down the press - well, isnt that a must anyway?Having this thing rocking around on the workbench doesnt make you nuts? I've taken my half ton press to 3000 lbs on my power to force gauge.. - hence the twisting of the gears-Thats three time the limit. I mean, If I only could safely get the rated force Id be more than happy. A two ton press with actual 4000 pounds or even 3500 would be great for me.
lloyd Posted July 1, 2017 Posted July 1, 2017 "I want to measure the force my press exerts on the target. The PTF gauge gives me a pressure value, so I need to know the pistons diameter. Or whats my mistake?"--------------No mistake. But... just to be precise about it, you need to know the piston's area. From that, of course, you can calculate the actual force on the piston at each graduation of gauge pressure. Then, divide that force by the area of the tooling on the powder, and you have the pressure per square unit on the powder. E.G.: Say your piston had a diameter of 1.26157" -- that's an area of 1.25 in^2. Say the pressure gauge read 1000psi. Then the force exerted by that piston at that pressure would be 1250lb. Now, say your tooling had a diameter of 0.7979" -- an area of 0.5 in^2. That would translate to a pressure on the powder of 2500psi. Lloyd 1
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