lone Wolf Posted Sunday at 11:24 PM Share Posted Sunday at 11:24 PM (edited) Have PDA gripper wire size .296 one side of handle hasPDA 102 other handle has 546 would like to know some history on this gripper Edited Sunday at 11:48 PM by lone Wolf 5 Quote Link to comment Share on other sites More sharing options...
liftyzig Posted Monday at 01:57 AM Share Posted Monday at 01:57 AM Not familiar with them personally but theres lots of posts on here about them around 2005-2006 https://www.google.com/search?q=hand+gripper+"PDA"+site:www.gripboard.com 1 1 Quote Link to comment Share on other sites More sharing options...
liftyzig Posted Monday at 02:19 AM Share Posted Monday at 02:19 AM From that search link I posted I found here on GB a link to the original store, which was gone but luckily theres wayback machine: https://web.archive.org/web/20050407033007/http://www.fractionalplates.com/cgibin/edatcat/PDAstore.cgi?user_action=detail&catalogno=9.15 3 1 Quote Link to comment Share on other sites More sharing options...
deadgrip Posted Monday at 03:24 AM Share Posted Monday at 03:24 AM They gave the most technical explanations on gripper springs that I’ve ever seen. $9.95 for one I remember these… 2 Quote Link to comment Share on other sites More sharing options...
Cannon Posted Monday at 07:44 PM Share Posted Monday at 07:44 PM 17 hours ago, deadgrip said: They gave the most technical explanations on gripper springs that I’ve ever seen. $9.95 for one I remember these… I did find it interesting that they felt declaring the wire size was so critical. I mean... "Wire size is the only legitimate, truthful way to classify torsion spring grippers. Don't be hoodwinked into accepting model numbers or names that mask the lack of tolerances in all other respects." And later, "Maintaining model labels without wire size allows the provider to buy springs out the back door on an 'as available' basis, mark it any way he likes, and side step the responsibility to provide you with anything specific." Those are kind of wild statements in my opinion, but it was their motivation for stamping the spring size on the handle I guess. There have only ever been certain spring sizes available. And the build specs, in some cases, matter almost as much. I get that PDA was saying they were controlling that as well with fixtures and such, but we've seen this problem with spring supply for Standard. Nickel exists because they are mistakenly wide Iron springs. So no matter how we built them, fixtures or not, they would be too hard even though wire size is correct. Same problem with Copper but they would be too easy no matter how we built them. And again with Chromium. The first two mistaken batches of those were all too narrow and therefore were like hard Tungstens even though the wire size is so much bigger (0.312 versus 0.331). We have also found that spring suppliers to this day have a very tough time controlling the preload angle. Most of the time they want to quote us a +/- 5% tolerance on our desired angle. That is completely unmanageable. If you take a 0.283" Iron spring at 21° that will be easier than a Platinum. At 26° it might be a really nice gripper. At 31° it would be harder than Cobalt. There is only so much you can do with the mount to correct for this. If you're trying to arrive at a certain strength for a gripper, an analogy that I would give is like locating a specific point on a map. Let's say the target is Minneapolis. Wire size is like saying "The location is in the Mid-West." Choosing a spread is like saying "The state is Minnesota." (The point here being that choosing a different spread on the same wire size already has you in the entirely wrong state for your target. You're not likely to correct course with coil size and mounting depth adjustments.) Coil Size would be like saying "This city is located in Hennepin County." (This really hones you in because it has to be chosen before springs are run. You can't really play around with coil size after the fact. You have to pick a size and then run springs.) Mounting Depth would be the final adjustment like a street address. So, yeah, wire size is critical to get you to a certain area and is important in that respect. But once you're in that area, there are still many directions you can head. And wire size is literally the easiest thing to get right. You just order that wire.. done. From the sounds of it, maybe that used to be a problem. This is a good paragraph on their product page although I don't know who it's directed towards. I'm not sure who was using whatever springs they could get willy-nilly: "The facts of life are that typical torsion spring gripper suppliers do not build grippers from the ground up – they are assembled from mass-produced springs with 'manufacturer friendly' tolerances and other parts, which also have slack tolerances. If the wire size they normally use is not available, they will use whatever wire size is available - but they don't change the model number to reflect the change. Since this is common practice, they literally cannot set out to build one gripper that requires a specific closing force or has a precise included angle or skew using each required component – they are limited to the characteristics those components. Nor can anyone pop out gripper after gripper that has the same rating. Once the spring has been wound its characteristics are set until fatigue (seasoning by cycling) or tampering (e.g., the application of heat) are applied." So I guess stamping the spring diameter on the handle addressed that problem for the savvy buyer. And they are right, it's exceedingly difficult to pop out gripper after gripper with same rating. It's just not because of wire size. It kind of is actually because of everything else, especially what they call "included angle." 4 Quote Link to comment Share on other sites More sharing options...
John Knowlton Posted Monday at 07:49 PM Share Posted Monday at 07:49 PM it would be nice to have one these some day 1 Quote Link to comment Share on other sites More sharing options...
Cannon Posted Monday at 08:50 PM Share Posted Monday at 08:50 PM 1 hour ago, John Knowlton said: it would be nice to have one these some day Agree. They are extremely rare. I cannot remember the last one I ever saw for sale. 1 Quote Link to comment Share on other sites More sharing options...
liftyzig Posted Monday at 09:26 PM Share Posted Monday at 09:26 PM (edited) 1 hour ago, John Knowlton said: it would be nice to have one these some day Aren't you the guy that made them? Edit: Sorry, Mixed up my Johns (LOL) John Szimanski is who I was thinking of (apparently passed in 2009, RIP ) Edited Monday at 09:30 PM by liftyzig Quote Link to comment Share on other sites More sharing options...
John Knowlton Posted Monday at 09:33 PM Share Posted Monday at 09:33 PM no worries, Johns are easily mixed up 1 Quote Link to comment Share on other sites More sharing options...
bencrush Posted Monday at 09:41 PM Share Posted Monday at 09:41 PM (edited) I had two PDA grippers many years ago. Probably sold them, like an idiot. Or traded them. I don't remember what happened, but I know I don't have them anymore. One of them I'm pretty sure was a .280" spring. The other I don't remember at the moment. Edited Monday at 09:43 PM by bencrush Quote Link to comment Share on other sites More sharing options...
liftyzig Posted Monday at 09:53 PM Share Posted Monday at 09:53 PM I'm curious why the wire size from the OP isnt on the handles then.. ? Quote Link to comment Share on other sites More sharing options...
lone Wolf Posted Monday at 10:57 PM Author Share Posted Monday at 10:57 PM I got this gripper awhile back from a guy called soilworker Quote Link to comment Share on other sites More sharing options...
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