Tom Black Posted September 6, 2002 Share Posted September 6, 2002 I just posted a new article on my website which is the culmination of a lot of work and thinking over the last year. The article describes how to make an adjustable gripper that varies in strength by changing the length of the handles. Unlike a mere modified gripper, the length of an adjustable gripper can be changed at any time, adjusted shorter or longer. Click here: Adjustable Gripper Quote Link to comment Share on other sites More sharing options...
apdwler Posted September 6, 2002 Share Posted September 6, 2002 Very interesting. I have a project for the next weekend I don't work. Thanks Mr Black! Quote Link to comment Share on other sites More sharing options...
AP Posted September 6, 2002 Share Posted September 6, 2002 Excellent report tom! i will extend my old 3 as soon as my new 3 comes in the mail! much thanks to you tom! Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 7, 2002 Share Posted September 7, 2002 Simple but brilliant. My only concern is the possible wear and tear on the softer aluminum threads which might occur with frequent loosening and tightening of the steel bolts. Quote Link to comment Share on other sites More sharing options...
Tom Black Posted September 7, 2002 Author Share Posted September 7, 2002 I have that concern too, but forgot to mention it in the article. I've taken apart the prototype advanced quite a few times, one of my training partners who is just closing the #1 has been using it. The threads seem to flatten on the top where the edge is sharp but then stabilize and have stayed that way for about a month. I don't tighten the bolts on really hard. If the threads do wear out I could thread for the next sized bolt. This in theory could be done at least twice. The larger sized bolts would have courser threads and may not degrade as much. I'll let people know if I have a problem with the 1/4". I made an #3 extended yesterday, using a new double stamped unseasoned #3. I drilled like I said in the article, with a piece of tape around the drill at 1/2" so I wouldn't go in too deep. I highly recommend a starter hole with a small drill, I used a 3/32". The small drill won't drift as much and the center will hold true. With around 3/8" inches of thread the handle seemed very stable and I was able to close the gripper with around 1/4" added to the end, which surprised me considering the #3 was unseasoned (and it was supposed to be a rest day). The gripper starts more springy than usual, but gets tougher toward the end. Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 7, 2002 Share Posted September 7, 2002 Tom have you considered replacing the 1/4'' steel bolt with a large head 1/4'' aluminum bolt ? Quote Link to comment Share on other sites More sharing options...
Tom Black Posted September 7, 2002 Author Share Posted September 7, 2002 No, I was unaware that aluminum bolts existed. They might be a good idea, hard to say without trying. Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 7, 2002 Share Posted September 7, 2002 They do exist. I have some 1/4'' standard thread large head. Quote Link to comment Share on other sites More sharing options...
terminator Posted September 8, 2002 Share Posted September 8, 2002 Tom, if you use aluminum bolts on aluminum, be sure to use ample anti-seize. Otherwise those suckers will gall immediately and you're stuck. I don't think you will have problems with steel bolts, there isn't enough stress to make a difference if they're tightened properly. Also, Heath's modified #4 was quite a bit harder than just about every #3 or elite I've seen, I call that thing the pinky remover. Quote Link to comment Share on other sites More sharing options...
Marc Posted September 8, 2002 Share Posted September 8, 2002 Tom, You could use Heli-coil inserts to stop the soft aluminum thread from stripping. Any good hardware shop should be able to fix you up. Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 8, 2002 Share Posted September 8, 2002 Marc has the solution see here. http://www.emhart.com/products/helicoil/Default.htm Quote Link to comment Share on other sites More sharing options...
Guest mg6680 Posted September 9, 2002 Share Posted September 9, 2002 I showed my machinist neighbor Tom's article and he too suggested the heli-coil. Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 19, 2002 Share Posted September 19, 2002 Tom, I like your idea, but am afraid of screwing up and ruining a gripper. If I had a decent drill press and vise it would be easy to do. Have you considered contacting Warren Tetting with the idea of having him manufacture your adjustable gripper? Quote Link to comment Share on other sites More sharing options...
Tom Black Posted September 20, 2002 Author Share Posted September 20, 2002 Oldguy, What are your chief concerns? It sounds like you don’t have a vise, I guess it would be hard to do this without one. Without a vise it would be impossible to drill the holes straight and cut the segments. If it is the problem with the threads, I haven’t had a problem yet, but I could foresee that it might be a problem. The Heli-coil sounds like the answer. For commercially made grippers they might have to be made that way for warranty purposes. If you just drill and tap a #3 or #4 then you wouldn’t have to cut the gripper and the gripper could be used even if the threads eventually wear out. One thing I have discovered now that I’ve made an extended #3 is that very little thread is needed to secure the segments, I’ve had a ¼” segment bolted on with maybe only 1/8” of the bolt going into the main handle segment with no problems. As far as Tetting is concerned, there is also a possibility of going back to steel for the handles. I’m not sure why he went to aluminum, probably because of weight. I’ve actually toyed with the idea of making the entire gripper myself (spring and all), perhaps emboldened by my success with doing this modification successfully. It doesn't seem that much harder to make the entire gripper compared to what I've already done. I could make in-between spring sizes. Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 20, 2002 Share Posted September 20, 2002 What I am saying is that some people would like to use your gripper ideas, but do not feel confident enough, or be equipped to do it. They might want to pay someone else to do it for them. So Warren Tetting came to mind. I think you have thought it out very well and have everything covered. Quote Link to comment Share on other sites More sharing options...
Bill Piche Posted September 20, 2002 Share Posted September 20, 2002 What I am saying is that some people would like to use your gripper ideas, but do not feel confident enough, or be equipped to do it. They might want to pay someone else to do it for them. So Warren Tetting came to mind. I think you have thought it out very well and have everything covered. Actually, the thought came to mind for paying Tom to do it. Quote Link to comment Share on other sites More sharing options...
OldGuy Posted September 20, 2002 Share Posted September 20, 2002 I was hinting at that in a roundabout way. Trying to be less blunt and direct as part of my new image. Quote Link to comment Share on other sites More sharing options...
Guest O1d Dude Posted September 20, 2002 Share Posted September 20, 2002 Indeed. Quote Link to comment Share on other sites More sharing options...
Guest mg6680 Posted September 20, 2002 Share Posted September 20, 2002 Its a fairly expensive one time investment for the helicoil wrench and tap tho. About $15 for the wrench to insert it into the tapped hole. Quote Link to comment Share on other sites More sharing options...
Tom Black Posted September 22, 2002 Author Share Posted September 22, 2002 Well, I’m far from a professional machinist. My gripper is certainly good enough for an amateur attempt, but it is not drilled perfectly or cut perfectly (I did get better with practice, however). Problem with making them for sale would be that my standards would have to be even higher. I could foresee making a jig for both the drilling and cutting of the handles, this would be a factor in making them to a higher standard. I don’t have a drill press either, which I feel I would need if I started making a lot of these. Quote Link to comment Share on other sites More sharing options...
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