dangerousamateur Posted April 26, 2015 Posted April 26, 2015 Finally I found a place to set up a small arbor press, similar to this thing here:http://www.harborfreight.com/1-ton-arbor-press-3552.html Question is, how would, or how do you shield yourself when you use such a thing?Somehow there is always a conflict between the handle and the shield. I'd also like work with whistle and maybe even strobe, so I will need some protection. Another questions:I'm going to add a platform under this thing to fit 1lb motors. First question:Now these cheap things are rated 1000Kg - can one reach that in practice, or is it rather much less? The handle looks very short, and I bet the designer did not calculate with crazy pyros using cheater bars to mangle the gears. Second question:Some guys advocate waxed tubes and claim that much less pressure is needed in this case.1 ton on a 1lb motor makes something like 3000-4000psi or even less, not the 9000psi often recommended.How do you feel about that?
nater Posted April 26, 2015 Posted April 26, 2015 (edited) Without making some modifications to the arbor press, you will not be able to fit a 1# motor. The throat length is not tall enough to accomodate the length of the motor and tooling. If you do make the working height taller, the teeth on the ram will break with the force needed on 1# motors. It has been done, however. Personally, I use my arbor press quite a bit for 1/2" devices and smaller. It also works well for pressing individual stars. In the past, I have advocated pressing motors to 7500 psi. Lately, I have been pressing to 5000 and have eliminated some of the problems with certain comps creeping around the first rammer and locking it in place.You can make a stand for a shield and set it in front of the press with just enough room for the lever. I have not bothered to do that. If I press whistles that small, they are used as inserts and have no core. With no spindle to pinch or source of friction, I feel the risk of an ignition during pressing is low. I do make cored 1/4" bottle rockets, but I do not feel one of them blowing nearby is terribly hazardous. Lastly, it seems most accidents with whistle involved removing a stuck spindle or rammer. The one accident involving actual pressing that I am aware of was attributed to strobe comp being pinched between the inside of the rammer and the spindle. Watch your do not pass mark and clean your rammers to prevent this type of accident. Edited April 26, 2015 by nater
dangerousamateur Posted April 26, 2015 Author Posted April 26, 2015 One of my thoughts was to let the shield end at the handle and only cover one side. I could then hide at that side and only expose my am to grip the handle... Watch your do not pass mark and clean your rammers to prevent this type of accident.Mistakes do happen. Besides I also have a sleeve for my 12,7mm rockets that resembles the ones from Wolter.How does aluminium behave in pipe bombs? The screws are rather massive, M4. I wonder what would happen in this case, will the pressure shoot the rammer out, ripping the gears? Is detonation possible?
MrB Posted April 26, 2015 Posted April 26, 2015 First question:Now these cheap things are rated 1000Kg - can one reach that in practice, or is it rather much less? The darn thing states straight out of specs that it has a 20:1 ratio, which doesn't seam unlikely. That means you need to put about 50 kilos on the far end of the lever to get a ton straight down. I'd be more worried about breaking it from using to much force, then not being able to reach max force. Which is probably why the lever is so short to start with. Well, that, and the fact that a significantly longer lever would be quite cumbersome to use when the darn thing has to be turned more then a half revolution.B!
GMetcalf Posted April 27, 2015 Posted April 27, 2015 How does aluminium behave in pipe bombs? The screws are rather massive, M4. I wonder what would happen in this case, will the pressure shoot the rammer out, ripping the gears? Is detonation possible? I don't think the gears would break with a device the maximum diameter an arbor press that size would accommodate (i.e. a half inch) but with something like whistle mix, it would indeed detonate. I think the biggest risk would be bits flying out sideways, although I believe Aluminium (correct me if I'm wrong) doesn't shatter like brittle metals such as iron/steel do. The Aluminium sleeve will probably just split like a drinks can. I expect there will be someone on this forum who's had something explode while being pressed and can share their story? I personally tend to only use wooden rammers for everything except plain Black Powder so if anything does explode there won't be any hefty bits of metal flying through the air... Personally I wouldn't want to be anywhere near a press being used to produce any sized whistle device without a decent sheet of plexiglass in the way. But then I am over cautious with everything and still wet myself every time I make Flash Powder. I think having only one hand exposed at the side of the screen ought to be alright, provided you're wearing leather gloves while doing this.
schroedinger Posted April 27, 2015 Posted April 27, 2015 What do you think about making a shield out of two plates. One i front of the press which leaves enough room for the handle, best made from lexan and a second shield right between the press and handle. If you place them close enough to the press and there should be enough place to still work conforrable. An other idea is to use a 90º section of a lexan pipe placed quite close to the press.
dangerousamateur Posted April 30, 2015 Author Posted April 30, 2015 So it's possible to use a 1t press for 7/8 BP motors.But Ned does not use any kind of shield. Scary even if BP somewhat safe.So a 2ton version with extended height should do 3lb engines? I mean, if that works so nicely, and so much faster then pumping these hydraulic car jack equipped frame things, it sounds like the real deal. I do make cored 1/4" bottle rockets, but I do not feel one of them blowing nearby is terribly hazardousI agree, but how about 1lb engines and sleeves? But I'm really wondering, I searched the internet for quite some time, but I never found any example of an arbor press with a shield... Do all the arbor press guys work without one or what?
nater Posted April 30, 2015 Posted April 30, 2015 Like I said above, it is possible to press larger motors on an arbor press like that, but you will eventually wear out the teeth with the higher pressures. This will happen much faster if you use a cheater bar on the handle. In fact, it was one of Ned's arbor presses that he damaged with over pressing at an event. Arbor presses are faster than hydraulic bottle jack presses, which is why I like them for smaller devices. Most people who I have seen use arbor presses, do not use a shield with them. I don't use a shield on my arbor press, but I also do not use it on devices that are more prone to an accidental ignition. I also take care to not pinch the spindles and keep my rammers clean. There is a huge difference between a 1/4" cored motor and a 3/4" cored one. I would not want a 1 lb motor to CATO near me, with or without a shield. I do use a shielded press when pressing 3/4" motors. I still think the chance of an accidental ignition during pressing is very small. It is far more likely to be a problem when you are pulling the spindle or removing a stuck rammer.
Mumbles Posted April 30, 2015 Posted April 30, 2015 As Nater mentioned, a shield can be secured to an arbor press. There's an example of one toward the bottom of this page for what it's worth. http://www.thecalderwoods.org/tom/blastShield2.htm You don't see a lot of them, that's for certain. Probably just because anyone who does serious pressing or make serious rockets all have hydraulic presses. Arbor presses are largely reserved for smaller rockets and inserts.
oldspark Posted April 30, 2015 Posted April 30, 2015 (edited) http://www.amateurpyro.com/forums/topic/6743-modified-arbor-press/Post number 13 Edited April 30, 2015 by oldspark 1
MrB Posted April 30, 2015 Posted April 30, 2015 http://www.thecalderwoods.org/tom/blastShield2.htm You.... You really need to stop posting links. If it's not on your end, then Sidewinder needs to talk the forum outside for a small talk, beat it up, using a short wooden dowel, and one it's beaten to submission, get it back on track, so that this stops happening. I know there are people who are proud to be in the 1% club's, but, your in a class of your own. %C2%A0. What ever that is. (Oddly enough the link points to *.htm%A0 when i point on it, but if i copy / click it, it turns out to point to *.htm%C2%A0. That to shouldn't be happening.) B!
Shunt Posted May 3, 2015 Posted May 3, 2015 http://www.thecalderwoods.org/tom/blastShield2.htm This link works for me, hope it helps.
mikeee Posted May 3, 2015 Posted May 3, 2015 On most of the blast shield examples shown, most of them could use large washers under the nuts to provide more support to restrain the shield from pulling away from the frame. The washer distributes the force over a larger area reducing the failure of the shield and shear forces on the bolt.
dangerousamateur Posted May 9, 2015 Author Posted May 9, 2015 Thanks guys. The shields look rather small, the covered angles behind it are not very wide. On the other hand I could enlarge the shield on the side opposite to the handle. http://www.thecalderwoods.org/tom/blastShield1.htmMaybe i overlooked that, but do you know how much fuel in what kind of motor they used in this test? I mean If it was a 1lb LWS motor with 80-100g fuel it would make me feel somehow comfortable, if it was some little 1/2 motor with maybe 15g rather not so much
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