Sean Dockery Posted March 28, 2012 Share Posted March 28, 2012 (edited) I've been thinking about ways to simulate the "rotation" that we feel when working with fixed thick bar. Things like the Monster Barbell, the Inch, et cetera. Yesterday I made these collars. http://www.youtube.com/embed/vO7h-GKc8j8 They work very well. On a dumbbell, or a barbell they lock the plates onto the bar in a way that feels very similar to the one piece challenge bells. Edited March 28, 2012 by Jedd Johnson (trying to get the video to show here but I can't figure it out - Jedd) Quote Link to comment Share on other sites More sharing options...
steve0 Posted March 28, 2012 Share Posted March 28, 2012 Great idea. I've been working on an idea of one, kind of like a pro style dumbbell. The dumbbell would have a fixed weight at around 80lbs or so with threaded 1" holes in the center of each end of the bell. Different size bolts could be added with weight plates. Hopefully this will keep the plates tight enough that they will not roll. Quote Link to comment Share on other sites More sharing options...
AdamTGlass Posted March 28, 2012 Share Posted March 28, 2012 slick idea. only neg is the biggest plates are inside you get leverage off the forearm during the lift, which can be a massive help. i think this will work well Quote Link to comment Share on other sites More sharing options...
mightyjoe Posted March 28, 2012 Share Posted March 28, 2012 A much simpler process is to use soft rubber disc between the DB plate stops and the first plate and then another one between the outer plate and the collar. Creates a spring effect. Once you apply pressure on the collar and tighten, everything becomes ONE unit. Thought of this a couple of years ago. Works very well and is simple and cheap. I cut out the rubber with scissors. Drew an outline from one of the collars used. Quote Link to comment Share on other sites More sharing options...
Sean Dockery Posted March 28, 2012 Author Share Posted March 28, 2012 Adam, Reckon you could change the plate order and still have the collars work? Joe, I tried the rubber idea several years ago and was never satisfied with it. Quote Link to comment Share on other sites More sharing options...
Bill Piche Posted March 28, 2012 Share Posted March 28, 2012 PDA had a pair of non-spin collars using this same concept. It worked well to keep the plates in place. Quote Link to comment Share on other sites More sharing options...
daniel reinard Posted March 28, 2012 Share Posted March 28, 2012 Adam, Reckon you could change the plate order and still have the collars work? Thats what i do. Keeps one from cheating at max efforts. Very cool idea Doc! Quote Link to comment Share on other sites More sharing options...
mightyjoe Posted March 28, 2012 Share Posted March 28, 2012 Adam, Reckon you could change the plate order and still have the collars work? Joe, I tried the rubber idea several years ago and was never satisfied with it. Sean, I'll post a pic with explanations. It will not move. Guaranteed! I used 2 different kinds of rubber before getting it right. Too thick will not work either but more importantly it's the rubber I used. Went up to 260 lbs and forcefully tried to make the plates shift. Nope! Simple! Cheap! and Works! Quote Link to comment Share on other sites More sharing options...
Sean Dockery Posted March 28, 2012 Author Share Posted March 28, 2012 Bill, I assumed someone had made these before. It's too simple an idea for me to be the first to think of it. Joe, I believe you. I made these for two reasons; 1) as a training tool for The Inch Project; and 2) as the first thing I've made using a boring bar setup on my lathe. Quote Link to comment Share on other sites More sharing options...
acorn Posted March 28, 2012 Share Posted March 28, 2012 Nice Job Doc! Now if we can just get you cutting threads you will be all set. I was just thinking about this project of yours a few moments ago and had an interesting idea. One who is Lathe positive like yourself could take some sacrificial cheapo plates and face off the lip and hub to make flat plates. 10's, 5's 2 1/2's Then after having a flat set proceed to cut the appropriate spherical profile on the outside diameter so that when fully loaded on your DB handle you will have solid spheres. Would take a bit of time but would make for a pretty neat progressive increase setup that would exactly mimic the interesting dynamics of the globe DB's. I may just have to do this myself if I can squeeze in the time one day. Prolly cheaper than buying the steel blanks at that diameter to do the same thing. - Aaron Quote Link to comment Share on other sites More sharing options...
acorn Posted March 28, 2012 Share Posted March 28, 2012 Actually thinking more on my previous post starting with Standard instead of Oly plates would eliminate the faceing operation and you would just have to bore out the hole. This would likely provide a much better fit to the DB handle ends than the standard cheapo's hole and you could really get the sphere to line up well. I may just have to make up a set of these for my circus bar. Best of luck on the project. - Aaron Quote Link to comment Share on other sites More sharing options...
mightyjoe Posted March 28, 2012 Share Posted March 28, 2012 Bill, I assumed someone had made these before. It's too simple an idea for me to be the first to think of it. Joe, I believe you. I made these for two reasons; 1) as a training tool for The Inch Project; and 2) as the first thing I've made using a boring bar setup on my lathe. No problem Sean! I didn't mean it that way my friend. I just love sharing ideas and yours is a good one! One could also take a floor flange with threaded holes (5/16" maybe) and place them flat against the plates you have loaded onto the DB. Then load the plates and attach your normal collars and tighten the outside collars. Next, screw the correct size bolts (2 should do) into the flanges until the bolts tighten against the weight plates. PRESTO! The plates WILL NOT move! What do you think Sean? I thought of this idea on the way home from work today. I think I will give it a whirl Sunday and see how this works. I will take pics and post them in my gallery. Thanks for motivating me to think of this! No drilling. No lathe work. Just purchase 2 flanges and 4 bolts that will screw into the flanges and you got it. I'll do it first as a TEST run before anyone else goes out spend any money. Lastly, if I sounded offensive in my previous post I certainly didn't mean it and I apologize. Quote Link to comment Share on other sites More sharing options...
Sean Dockery Posted March 29, 2012 Author Share Posted March 29, 2012 Aaron, Yes, I've been thinking of the same idea. Another thought was to cut keyways in the plates and the dumbbell using my shaper. 'Cause you know...I can. I've been thinking about how to use the stuff I have to replicate the Monster Barbell. These smaller things are ways to work up to that. And yes, thread cutting is on the agenda. Joe, No offense taken. You do seem to be missing my statement that using the lathe to make these was more than half the point. There are lots of ways to achieve similar results without using machine tools. But, none of those solutions gets me better at using machine tools. Quote Link to comment Share on other sites More sharing options...
mightyjoe Posted March 29, 2012 Share Posted March 29, 2012 Aaron, Yes, I've been thinking of the same idea. Another thought was to cut keyways in the plates and the dumbbell using my shaper. 'Cause you know...I can. I've been thinking about how to use the stuff I have to replicate the Monster Barbell. These smaller things are ways to work up to that. And yes, thread cutting is on the agenda. Joe, No offense taken. You do seem to be missing my statement that using the lathe to make these was more than half the point. There are lots of ways to achieve similar results without using machine tools. But, none of those solutions gets me better at using machine tools. No problem. Good luck on your lathe! I would love to have a lathe! Quote Link to comment Share on other sites More sharing options...
Shoggoth Posted March 29, 2012 Share Posted March 29, 2012 That's a great idea for the circus bar Aaron! I think you could buy plate to work cheaper though. If you got 12" or 14" x 1/2" flatbar and get the supplier to cut them in squares. You may be able to get the flatbar in thicker measurements as well. Wil a little math you could buy down to the lowest width you'd need as well. We but it all the time for making pile caps. (null) Quote Link to comment Share on other sites More sharing options...
climber511 Posted March 29, 2012 Share Posted March 29, 2012 There are lots of ways to do this project at a very professional level - but unless you are like Aaron and Doc and have access to a machine shop at no cost it's going to get very expensive very quickly. You will also run up against the density difference between steel and cast at some point depending on what you use as your raw material. Making a plate changing type set up looks fairly easy if cost is no object and you have a machine shop along with the skills to do everything needed. I may stop in and ask for an estimate where I deal just out of curiosity. And also ask him how he would go about making it - I have a couple ideas but no machinist knowledge to know if my way is as good as his way. Quote Link to comment Share on other sites More sharing options...
acorn Posted March 29, 2012 Share Posted March 29, 2012 That's a great idea for the circus bar Aaron! I think you could buy plate to work cheaper though. If you got 12" or 14" x 1/2" flatbar and get the supplier to cut them in squares. You may be able to get the flatbar in thicker measurements as well. Wil a little math you could buy down to the lowest width you'd need as well. We but it all the time for making pile caps. (null) Not that I have time to implement this right now but I already messed with the math on this to do that. Was thinking 1/2" or wider plate for inside plates out to just past center, then 1/4 or thinner the rest of the way for micro loading capabilities. I have a source for pre-cut sheet rounds in 1/8" OD increments up to 1/4" thick. In all likelyhood though to do an adjustable plate loaded DB in the manner I was thinking with machining time and materials would be a good bit more expensive than just buying an Inch replica DB. Might still be a fun project. I can't remember ever having to cut spherical profiles on a manual lathe when I was a machinist. So Just attempting to do that would likely make it worth it to me. Especially with the challenges of doing it across multiple pieces. On a CNC lathe it would be easy but what is the fun in easy! - Aaron 1 Quote Link to comment Share on other sites More sharing options...
acorn Posted March 29, 2012 Share Posted March 29, 2012 Aaron, Yes, I've been thinking of the same idea. Another thought was to cut keyways in the plates and the dumbbell using my shaper. 'Cause you know...I can. I've been thinking about how to use the stuff I have to replicate the Monster Barbell. These smaller things are ways to work up to that. And yes, thread cutting is on the agenda. Joe, No offense taken. You do seem to be missing my statement that using the lathe to make these was more than half the point. There are lots of ways to achieve similar results without using machine tools. But, none of those solutions gets me better at using machine tools. Very cool, Interesting idea on the keyway. That makes me think of pics I have seen of the Old Milo Triplex bells. There was a plate loading half and shot loading half to each globe. The plate loading half had profiled plates that just fit within the outer globe shell and had a large notch cast into the OD of the plates that acted as a keyway. The outer globe had a "key" rib cast into it. They fit together when closed to keep the plates from spinning. Everything that is old is new again. As I've said before Doc if you every need someone to bounce this machining stuff off of give me a call or email. Happy to help another tinkerer. If you don't have my number let me know. - Aaron Quote Link to comment Share on other sites More sharing options...
Shoggoth Posted March 29, 2012 Share Posted March 29, 2012 I can sure tell the stuff I wrote on my phone lol! If a guy got really fancy a set of pins/insets could be on each plate, just enough that it causes the plates to interlock. Really getting fancy now haha! Like Chris was mentioning too if this was made to the same dimensions of the Inch but using rolled steel that weight would jump substantially. If the perfectly round weight would be in the 140 range then each 1/2" plate would probably add 15# or so, so at full weight maybe slightly cylindrical but able to go well past Inch weight. I think I need to learn how to machine steel lol Quote Link to comment Share on other sites More sharing options...
Sean Dockery Posted March 29, 2012 Author Share Posted March 29, 2012 Aaron, I still have your number. I will definitely call here and bounce some ideas off you. The biggest thing I keep trying to do is come up with projects that require new skills, or a refining of existing skills. That way shop time is "productive". I'm trying to imagine the setup to cut a spherical profile over that large a diameter on a manual lathe. Or would you just work by hand and eye testing the cut to a shape you have? Almost like a sheet metal worker will hammer at a shape and compare it to a buck? Quote Link to comment Share on other sites More sharing options...
acorn Posted March 29, 2012 Share Posted March 29, 2012 Aaron, I still have your number. I will definitely call here and bounce some ideas off you. The biggest thing I keep trying to do is come up with projects that require new skills, or a refining of existing skills. That way shop time is "productive". I'm trying to imagine the setup to cut a spherical profile over that large a diameter on a manual lathe. Or would you just work by hand and eye testing the cut to a shape you have? Almost like a sheet metal worker will hammer at a shape and compare it to a buck? Sounds good, That is the best way to learn. I used to teach Lathe and shop math during a once a month Saturday program that the company I apprenticed with sponsored at the local community college for HS students interested in competing in the skill contests. So if there is some specific thing you are getting stuck on let me know. Its been close to 15yrs since I was a machinist and 20 since I taught but I can still prolly help you figure out good projects to acquire the skills you need to be proficient if you want some help. As far as the spherical profile, you could work by hand with a template. Roughing in with the cutter then finishing with a file but that would take forever with a sphere that big. You could also build a scaled up version of this or something similar. I'm sure there are prolly other versions out there but this one should get the idea across. I would prolly build something based on this tool's idea. If you decide to tackle this, let me just say I have no doubt you can do it, but I think cutting threads is easy by comparison. - Aaron Quote Link to comment Share on other sites More sharing options...
acorn Posted March 30, 2012 Share Posted March 30, 2012 Here is a thread where the author was making a quick change toolpost with some spherical parts. She used the template and file method I believe. http://www.practicalmachinist.com/vb/south-bend-lathes/machining-mla-23-toolpost-174336/ If you are not a member there yet might I recommend joining. Lots of stuff like this there. - Aaron 1 Quote Link to comment Share on other sites More sharing options...
bwwm Posted March 30, 2012 Share Posted March 30, 2012 I would guess using a template is pretty accurate, but if you need to check roundness, you can always take a roll of tape or some other round hoop and place it on the piece in various locations. Any areas that are out of round will make themselves apparent. This is a trick I use for wood turning spheres by hand. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.