Astro_Al Posted February 22, 2011 Share Posted February 22, 2011 Hi guys, I'm just waiting for a Massey to become available, but need something 'small' in the meantime. I've been looking at the KA75 and figure it'd do just fine for what I need. I need something I can stick together fast & easily. Being in the UK, I'm not going to buy one. So I looked for threads of similar builds. All I could find was one (very nice) completed hammer (by Youngdylan) and an idea for a hammer by Sam Salvatori(? - sorry, can't remember exactly). Does anyone know of any similar builds / threads I can find info in? I'm kind of surprised it hasn't been imitated more often. My over-simplified idea is a 7" solid round column and a single ram, double acting. I know it means more air, but that's not a serious issue. Any benefit in running the raising stroke of the ram at lower pressure to save air, or not worth the bother? My only other real quandry is the guides - I take it regular linear bearings would last about 30 seconds in this application? So what is the best alternative - bronze bushings and ground / hardened bar for the guides? Thanks for any pointers, I just need to throw this together over the next few weeks for a job starting in April - simple is good. Cheers, Al. P.S. - how do I find the threads I'm 'watching'??? Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 22, 2011 Share Posted February 22, 2011 My only other real quandry is the guides - I take it regular linear bearings would last about 30 seconds in this application? So what is the best alternative - bronze bushings and ground / hardened bar for the guides? Al, I'm not sure I follow you here. To my way of thinking the guides only need be cold rolled bar to back up the bronze, or plastic bushings, yes plastic. There are some new products out in plastic that are great (at least new to me) I could find out more if you wish. Also I can't see a problem with linear bearings, I've never had any problem with them in hammers........Or can't I see the forest through the trees.........mb Quote Link to comment Share on other sites More sharing options...
monstermetal Posted February 22, 2011 Share Posted February 22, 2011 Linear bearings can't handle the side loads, been down that road Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 22, 2011 Share Posted February 22, 2011 Ok, how does a K75 create side loads??? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted February 22, 2011 Author Share Posted February 22, 2011 Hmm, that's what I suspected Monstermetal. Could you flesh out your response a little in terms of situation, size of bearings etc & how long they lasted? So you would suggest using a bronze alloy or plastic-based solid bearing surface instead? I wasn't sure about the dimensional accuracy of cold rolled stock (in terms of running against a bearing surface) - if I don't need to find some ground & hardened bar stock that'll help considerably. Macbruce - I suppose there will be non-axial loads on the bearings due to the off-axis location of the ram in these machines. Cheers, Al. Quote Link to comment Share on other sites More sharing options...
MattBower Posted February 22, 2011 Share Posted February 22, 2011 I recall Larry posting something a while back about pouring Babbit bearings during a rebuild of a KA150. So I'm betting that's a clue. Larry? Macbruce, I would think that any time you put work between the dies that wasn't perfectly flat, or perfectly centered, you'd get some side load. Quote Link to comment Share on other sites More sharing options...
macbruce Posted February 22, 2011 Share Posted February 22, 2011 Duh, My memory isn't always the greatest source of reference. Having just looked at a k75 and I'm on the same page. Seems all hammers have to deal with side load, I would think the k75 less so with two guides. I've never had a hammer fail on account of that, just get sloppy , then adjust, shim, then replace. Course shimming a round bearing is really tough. I can't see how hardened ground shaft would prevent bearing wear any less, or are you expecting less deflection? I doubt the ka uses it, Bob's too cheap, what's in Youngdylan's................mb Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted February 22, 2011 Author Share Posted February 22, 2011 I don't know about youngdylan's - hoping he'll post up with what he did. Matt - haven't seen the ka150, is that made by the same guys as the ka75 (no reference to it on their page?). Cheers, Al. Quote Link to comment Share on other sites More sharing options...
MattBower Posted February 23, 2011 Share Posted February 23, 2011 The guy who invented the KA75 is Grant Sarver (Naked Anvil), who posts here on IFI. Grant made the KA150 as well, and as far as I know it's basically the same design, but I don't think he ever did the 150s on a production basis. Quote Link to comment Share on other sites More sharing options...
todoned Posted February 24, 2011 Share Posted February 24, 2011 I am not convinced that linear bearings would not work. Perhaps they need to be correctly sized for side loads, but why wouldn't this work? My power hammer uses a linear slide - integrated cylinder and bearings -- its not particularly beefy -- 3/4" rod for the bearings, hammer weight is 30+ pounds. No problems, several years of use. Might not be able to justify the cost when building to sell, but if building for yourself, and you can purchase the bearings used on E-bay, it seems feasible to me. -Tod Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted February 24, 2011 Share Posted February 24, 2011 I can't see how hardened ground shaft would prevent bearing wear any less, or are you expecting less deflection? I doubt the ka uses it, Bob's too cheap. Don't quite know where you would use hardened and ground shaft. The ram is guided by the cylinders. Quote Link to comment Share on other sites More sharing options...
monstermetal Posted February 24, 2011 Share Posted February 24, 2011 Well I have a couple of real beefy liniar bearings I bought at Boeing surplus with the idea of using them for guides on a hammer project. I think they are 1 3/8" rods... look real impressive but I started talking to the guys at the manufacture and they told me that they are not designed to handle jar or jolt type loads, but rather just weight.. the bearings are all housed in plastic and its surface area that supports the load, they will handle thosuands of pounds if its just sitting there and you want to move it.. but bang bang bang and they claim they will fail very quickly... and since they are very expensive when they get that big I decided to save them for something else... I think a stressproof shaft and a bronze bushing is the simple foolproof answer.. And yes my KA+150 has babbit slide bushings... when Grant built it he used some sort of epoxy babbit stuff and it had failed from age (cracked and broken).. the only place I found that was big bucks so just pouring babbit in there was a quick and simple fix... its worked perfect so far... Quote Link to comment Share on other sites More sharing options...
monstermetal Posted February 24, 2011 Share Posted February 24, 2011 I talked to Bob a bit about how they build the KA-75.... There is no shaft, the center rod of the cylinder is hollow tube that feeds the air, and thats not the guild, its the outer, larger tube that rides in the bushing...... as for guides they use a bronze bushing that is set in epoxy in a steel tube... that way they dont have to deal with all the alignment issues... they just clamp the dies togehter, pump the epoxy between the bushing and the steel tube, let it set and away you go.... Quote Link to comment Share on other sites More sharing options...
youngdylan Posted March 3, 2011 Share Posted March 3, 2011 I don't know about youngdylan's - hoping he'll post up with what he did. Matt - haven't seen the ka150, is that made by the same guys as the ka75 (no reference to it on their page?). Cheers, Al. Off the shelves sintered bronze bushes 1.5" ID with EN24T (4340) rods, regularly greased .... they've held up pretty well for about 2 years. To work well the guides that they bushes sit in (and the plate they mount to) need to be machined so the bores are reasonably parallel. Quote Link to comment Share on other sites More sharing options...
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