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Model Forum / General / Models / November 2006Turcite vs Moglice vs Delrin
Hi, I have been toying with the idea of making a 2 1/2D cnc router to cut out ribs etc for model airplanes. My thoughts for the slides were hovering around lengths of ground ms bar, the saddles being cut from box-section ms having holes drilled for plastic bearing bushes. I've read around and am trying to determine whether Turcite or Moglice or Delrin would be suitable for the bearing bushes ? I have found Delrin readily on eBay but I know the other two materials are specifically intended to be used in bearings, can anyone say which of these is best in this kind of low load application, and whether the advantages outweigh the convenience of Delrin ? Also a supplier of small quantities in diameters between say an inch and half an inch would be helpful. Many thanks,  SignatureBoo >Hi, > [quoted text clipped - 10 lines] > >Many thanks, Have you considered Glacier DU bushes? They're a steel/bronze/PTFE composite, I haven't used any for donkey's years & don't know if it's available now in standard sizes from the usual bearing houses but it might be quite good for that sort of job? Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service >Have you considered Glacier DU bushes? They're a steel/bronze/PTFE >composite, I haven't used any for donkey's years & don't know if it's [quoted text clipped - 6 lines] >Traditional & Modern canal craft repairs >Vintage diesel engine service Or how about Oilite bushes? Cheap and readily available. Or buy a length of leaded bronze and make some - I made the leadscrew bearings for my ML7 from this. Peter > >Hi, > > [quoted text clipped - 21 lines] > Traditional & Modern canal craft repairs > Vintage diesel engine service Excellent things DU bushes, every modern car would be lost without them. If you've got a car breaker local, bludge a couple of front suspension struts off him. That will give you good lengths of hard chrome bar and DU bushes, all good stuff for your router table. As cars come in various sizes so do the struts. Tom SignaturePosted via a free Usenet account from http://www.teranews.com I would seriously consider "ball bushing" bearings or whatever ball bearing type linear slides are around on ebay etc, plain bushings of whatever type are troublesome in the long run- I talk from industrial and home experience-alternatively computer printers are a source of this type of slide-good finish bar if bushes not salvageable, any independant computer dealer will have loads, as will your local council tip-but that is a case of dealing with jobsworths ( or bribes !) Mark G. > > >Hi, > > > [quoted text clipped - 4 lines] > > >whether Turcite or Moglice or Delrin would be suitable for the bearing bushes ? > > >I have found Delrin readily on eBay .. > I would seriously consider "ball bushing" bearings or whatever ball bearing > type linear slides are around on ebay etc, plain bushings of whatever type > are troublesome in the long run- I talk from industrial and home > experience... Your experience obviously doesn't include DU bushes. SignaturePosted via a free Usenet account from http://www.teranews.com Er.. well yes my experience does include DU bushes from 8 mm to 50 mm bore, they are good, but if you can get a ball bushing or other ball based linear slide cheap you will be on a better route to success.-Does any decent machine tool use otherwise ? DU bushes are esentially a leaded bronze bush with a ptfe coating,steel backed, great when new, but will not withstand well to intermitent side loads such as in a machine slide. Mark G. > > I would seriously consider "ball bushing" bearings or whatever ball bearing > > type linear slides are around on ebay etc, plain bushings of whatever type > > are troublesome in the long run- I talk from industrial and home > > experience... > > Your experience obviously doesn't include DU bushes. >>> I would seriously consider "ball bushing" bearings or whatever ball > bearing [quoted text clipped - 3 lines] >>> experience... >> Your experience obviously doesn't include DU bushes. They also can have some stiction compared to rolling element linear bearings. I used to use 1000's of 3/16" DU bushes on an instrument job I was involved with. We found we had to burnish the bushes to stop it. The shafts were mirror polished stainless steel. My recommendation for CNC use especially when using stepper motors is the lowest friction bearing you can find. Wayne... > >>> I would seriously consider "ball bushing" bearings or whatever ball > > bearing [quoted text clipped - 15 lines] > > Wayne... You blamed the bushes for the stiction? LOL SignaturePosted via a free Usenet account from http://www.teranews.com > You blamed the bushes for the stiction? LOL LOL Indeed. Do you think we didn't research the problem? This was a very low force application <10g. Nevermind clever clogs you obviously know more than the application engineers that helped us resolve it. But back onto subject DU's have no real place in this application. > > You blamed the bushes for the stiction? LOL > > LOL Indeed. Do you think we didn't research the problem? This was a > very low force application <10g. Nevermind clever clogs you obviously > know more than the application engineers that helped us resolve it. Obviously more than the designer who did the original specification. I've been using or specifying either Glacier or INA bushings and wear strips over 25 years, for units moving from 1 pound up to 10 tons, without having to resort to "application" engineers to create a workaround for a design fault. > But back onto subject DU's have no real place in this application. Says you... Based on one experience. I suggest you acquaint yourself with the INA Permaglide product application range. SignaturePosted via a free Usenet account from http://www.teranews.com > Obviously more than the designer who did the original specification. > I've been using or specifying either Glacier or INA bushings and wear > strips over 25 years, for units moving from 1 pound up to 10 tons, > without having to resort to "application" engineers to create a > workaround for a design fault. You know I didn't notice you there 15 years ago when this happened, maybe you were hiding in the closet. But I can assure you it was designed to the glacier recommended parameters. Tom each application has it's vices, what works well for one application may not work so well for another. In this case the instrument had very low internal force available to return the shaft to it's zero position. In the end it was made to work and well. But not quite so easily as Glacier said it would ;) But it's History now, and I'm glad I've moved on. >> But back onto subject DU's have no real place in this application. > > Says you... Based on one experience. I suggest you acquaint yourself > with the INA Permaglide product application range. No based on my cnc experience. No commercial machines that I know of use DU's and rarely do they use round linear ways except on the cheapest hobby machines. They just don't lend themselves to the rigidity required. There are tons of surplus linear motion items available on ebay etc, and the original poster might want to look to see whats available rather than re-invent wheels. I've seen lots of people get very annoyed and frustrated when their homebrew cnc's don't perform well. All my cnc milling machines use box ways, and bonded on Turcite as well as automatic lube systems. I've used more modern machinery with bolt on linear ways, and although nice and fast. SUCK for rigidity in many cases. > > Obviously more than the designer who did the original specification. > > I've been using or specifying either Glacier or INA bushings and wear [quoted text clipped - 34 lines] > on linear ways, and although nice and fast. SUCK for rigidity in many > cases. Wayne, the OP only wants to cut out ribs n stuff for model aeroplanes, most probably 20g tops... SignaturePosted via a free Usenet account from http://www.teranews.com > Wayne, the OP only wants to cut out ribs n stuff for > model aeroplanes, most probably 20g tops... Yes Tom I saw that. But having been around a lot of people doing homebrew retrofits as has J.S. I have seen so many start off saying "I only need this" But later wish they had made the machine to be capable of doing "That" ! Same with the size issue! Sadly reading through the posts on some of the CNC forums, there is quite a lot of frustration. Most of which could of been avoided with a little time spent earlier on planning the thing out. Wayne.. > No commercial machines that I know of >use DU's This one does. http://web.onetel.com/~duttondock/Pictures/Ward-1.jpg OK, I realise you probably meant current CNC machines, & this one is neither current nor CNC. I just thought I would throw it in to be mischievous. In fact it may well predate Turcite, Moglice etc., I don't know when they became readily available? Cheers Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service >> No commercial machines that I know of >> use DU's [quoted text clipped - 7 lines] > mischievous. In fact it may well predate Turcite, Moglice etc., I > don't know when they became readily available? Hehe.. Yes not CNC. I've seen an used a fair few Ward Capstans. But what the hell is that thing? I'm intrigued. Looks more like a t&c grinder?. >>> No commercial machines that I know of >>> use DU's [quoted text clipped - 11 lines] >what the hell is that thing? I'm intrigued. Looks more like a t&c >grinder?. Yes it is a controlled spiral cutter grinder, will grind spiral flutes without the use of guide fingers as well as all the usual T&C functions. Made by Ward Grinders in Dorset, spiral grinders were their speciality. No connection AFAIAA with the other lot. Cheers Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service > Yes it is a controlled spiral cutter grinder, will grind spiral flutes > without the use of guide fingers as well as all the usual T&C > functions. > Made by Ward Grinders in Dorset, spiral grinders were their > speciality. No connection AFAIAA with the other lot. Tim I actually thought after I posted that maybe it was a product of Ward Grinders in Parkstone, Poole. I have quite a few friends in the business who served their time there. Maybe some of them worked on your machine. Long gone now I think. Wayne... Just to throw another oar in the water here. I have had two personal experiences where the ball bushings were replaced by the plastic lined bushings from RS and worked better. Both were low force applications and both had problems with fine dust. One was on the Y axis of a laser cutter and the fine dust and fumes caused the ball bushing to tighten up in service. Once on a service call we couldn't get any new bushings locally in time and replaced them temporary with some RS lined bushes whilst spares were ordered. They never got fitted as the lined bushes wiped the shaft clean and it ran until it was scrapped a few years later. Because of this experience I swapped the ball bushing on a CNC router for lined bushings as the MDF dust was having the same problem and again it cured the problem. With better designed seals and covered bellows on the way the ball bushings may have been no problem but with the skeletal build up of both these machines the lined bushes cured what problems we had. . -- Regards, John Stevenson Nottingham, England. Visit the new Model Engineering adverts page at:- http://www.homeworkshop.org.uk/ > With better designed seals and covered bellows on the way the ball > bushings may have been no problem but with the skeletal build up of > both these machines the lined bushes cured what problems we had. Yes a problem with round linear rod is that need to support it, and therefore the slot required through the bearing to clear the supports. It is one of the reasons I dislike them. The longer the travel you need the worse the problem seems to get. As well as their need to be elevated over any solid base. Those NSk(etc) linear rails at least can be bolted down onto a flat surface. I do realise there's a cost issue with those though ;) There are bargains to be had if you look hard enough. Wayne... > No commercial machines that I know of > use DU's and rarely do they use round linear ways except on the cheapest > hobby machines. They just don't lend themselves to the rigidity required. I have to correct you. Industrial lathes with round linear ways do exist. *Big* round tubes with hydrostatic bearing (no DUs). Can't remember a name now. Nick Signature*********************************** *** Available now in NZ and AUS *** *********************************** <http://www.yadro.de> >> No commercial machines that I know of >> use DU's and rarely do they use round linear ways except on the cheapest [quoted text clipped - 3 lines] > Industrial lathes with round linear ways do exist. *Big* round tubes with > hydrostatic bearing (no DUs). Can't remember a name now. Nick.. You didn't see my disclaimer ;) "machines that I know of" I have used lathes with nsk style linear rails though. Two machines come to mind, both Mazaks (quickturn 10 and a 15) Both replaced old flatbed Hardinges. When it came to turning 316 stainless they effectively were slower than the 1979 and 1982 machines they replaced. The 15 had live tooling in the turret too, the rigidity so so poor it sometimes struggled to mill 6082 alloy. Those were very expensive machines too. ALl they were really good for was high speed rapids. You can't beat IRON and lots of it! The reason I seem to collect Hardinges ;) If they really have as you say "tubes" thats even worse, unless they are filled with some very high density material. Hate to think about the resonance problems. Wayne.. > Nick.. You didn't see my disclaimer ;) I thought you know them all. ;-) No, I thought that round beds are crap. Maybe they are. Now the name came back and I can give you a link. So you can judge by yourself. At least, it is interesting. Can't say wether it really works! <http://www.a.monforts.de/quickstart/index.php?id=104> > You can't beat IRON and lots of it! The reason I seem to collect > Hardinges ;) Yes, mass is always good. No doubt. Nick Signature*********************************** *** Available now in NZ and AUS *** *********************************** <http://www.yadro.de> > <http://www.a.monforts.de/quickstart/index.php?id=104> Sorry, we have that in English too! <http://www.a.monforts.de/quickstart/index.php?id=229&L=1> Nick Signature*********************************** *** Available now in NZ and AUS *** *********************************** <http://www.yadro.de> >> Nick.. You didn't see my disclaimer ;) > > I thought you know them all. ;-) Not them all! Seen a few ;) and been inside more than I have used. > No, I thought that round beds are crap. Maybe they are. > Now the name came back and I can give you a link. So you can judge by > yourself. At least, it is interesting. Can't say wether it really works! > > <http://www.a.monforts.de/quickstart/index.php?id=104> Well actually that looked rather good compared to slinky little linear rails. They say "solid bar" but it looks like a very thick wall tube. They must pump oil into the bearing. The rear slideway looks to be a box way or something else. There is no doubt a limit to how long they can produce a Z axis in this form. Shorter the better. They seem to be using linear rails on the X axis. >> You can't beat IRON and lots of it! The reason I seem to collect >> Hardinges ;) > > Yes, mass is always good. No doubt. The best linear rail machines I have seen still used an iron base, but it's still relying on all those little bolts. As machine tools can be very resonant beasts it can cause problems. Wayne... >>>> I would seriously consider "ball bushing" bearings or whatever ball >> bearing [quoted text clipped - 15 lines] > >Wayne... My old Summagraphics A0 pen plotter had a stepper driven head, and ran in plain oilite bushes on a ground 10mm shaft about a metre long. Did a fair bit of mileage in the 13 years I had it and a few more in the years before that. Still plotted perfectly with no stiction. Designed and built a few cutting machines for mirror lens that we moulded, and used plain bushes on a ground shaft too, in use everyday since 1996 and still going strong as far as I know. Ran via pneumatic & hydro-pneumatic motion rather than steppers though. However, I can't disagree with you about using the lowest friction bearings wherever possible, and linear ball bushings aren't that expensive now, and neither is hardened and ground shafting. Peter > My old Summagraphics A0 pen plotter had a stepper driven head, and ran > in plain oilite bushes on a ground 10mm shaft about a metre long. Did > a fair bit of mileage in the 13 years I had it and a few more in the > years before that. Still plotted perfectly with no stiction. The job I was talking about was a linear displacement transducer. Before use DU's the bearing was just the brass body of the instrument. This was broached to the correct diameter, which gave a fantastic action, but was expensive. Like you said can last a long time, I remember an instrument coming back for service after 15 million full stroke cycles (10mm) measuring Weetabix boxes! It was as good as new. The DU's were a cost cutting exercise, and once the problem was resolved it was perfect, but not as long lasting as the plain bearing. > However, I can't disagree with you about using the lowest friction > bearings wherever possible, and linear ball bushings aren't that > expensive now, and neither is hardened and ground shafting. Especially with steppers, they are rather sensitive devices. I tend to use servo's on my CNC's when I can. Wayne... >> My old Summagraphics A0 pen plotter had a stepper driven head, and ran >> in plain oilite bushes on a ground 10mm shaft about a metre long. Did [quoted text clipped - 19 lines] > >Wayne... For the benefit of the terminally bewildered - would somebody kindly tell me (and the majority of the other silent witnesses) what DU stands for! -- Chris Edwards (in deepest Dorset) "....there *must* be an easier way!" >>> My old Summagraphics A0 pen plotter had a stepper driven head, and ran >>> in plain oilite bushes on a ground 10mm shaft about a metre long. Did [quoted text clipped - 26 lines] > >Chris Edwards (in deepest Dorset) "....there *must* be an easier way!" Depleted Uranium......<bg> . -- Regards, John Stevenson Nottingham, England. Visit the new Model Engineering adverts page at:- http://www.homeworkshop.org.uk/ >>>> My old Summagraphics A0 pen plotter had a stepper driven head, and ran >>>> in plain oilite bushes on a ground 10mm shaft about a metre long. Did [quoted text clipped - 30 lines] > >. Get on with your work! -- Chris Edwards (in deepest Dorset) "....there *must* be an easier way!" >Er.. well yes my experience does include DU bushes from 8 mm to 50 mm bore, >they are good, but if you can get a ball bushing or other ball based linear [quoted text clipped - 13 lines] >> >> Your experience obviously doesn't include DU bushes. My Ward T&C grinder has DU slides Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service > Er.. well yes my experience does include DU bushes from 8 mm to 50 mm bore, > they are good, but if you can get a ball bushing or other ball based linear [quoted text clipped - 13 lines] > > > > Your experience obviously doesn't include DU bushes. Rubbish SignaturePosted via a free Usenet account from http://www.teranews.com >I have been toying with the idea of making a 2 1/2D cnc router to cut out ribs >etc for model airplanes. My thoughts for the slides were hovering around >lengths of ground ms bar, the saddles being cut from box-section ms having holes >drilled for plastic bearing bushes. Can't help on the bearings, sorry. But ground bar can be very expensive. I was looking for some a while ago for an overarm for a milling machine. I ended up buying hard chromed bar from a hydraulic ram supplier. How is the router itself 2 1/2D? Manual Z? Isn't that limitation only imposed by the CAM you use? > Hi, > [quoted text clipped - 11 lines] > > Many thanks, try this guy http://stores.ebay.co.uk/Marchant-Dice-Ltd I brought a couple of things from him usual disclaimer Andrew > Hi, > [quoted text clipped - 10 lines] > > Many thanks, You seem to be missing the point (as does everyone else) that Moglice is cast in place in a housing (it's mixed up like an epoxy) so getting the perfect fit is easy. It does suffer with high initial friction but the bearings bed in after a few cycles (in my experience). One thing to watch out for is that they don't get exposed to heat, we found that they tend to flow at >70C causing them to seize up (found during an elevated temperature storage test). Martin Signaturemartin<dot here>whybrow<at here>ntlworld<dot here>com Going off at a sort of tangent. Can anyone give me the addresses or web sites of suppliers of Turcite and Moglice in amounts suitable for the one off bloke like me? Many thanks Norman >Going off at a sort of tangent. Can anyone give me the addresses or web >sites of suppliers of Turcite and Moglice in amounts suitable for the >one off bloke like me? I bought a small quantity of SKC 400 ELF from a local company here in Sale a while back - its a PTFE filled castable epoxy. Planned to use it to re-do my lTaig mill feednuts till I discovered that the backlash was bearing end-play and crappy couplers - see my article in latest MEW. So, its still in its tin waiting for an excuse to use it on something - I'm sure I will find a use for it at some point! SKC's website: http://www.skc-technik.de/e/e_index.html UK dealer details: M. Buttkereit Ltd. Unit 2, Britannia Road Sale, Cheshire M33 2AD Tel. +44 (0) 161 9695418 Fax +44 (0) 161 9695419 info@buttkereit.co.uk Regards, Tony Tony, Many thanks from the once capital of the innovative industry. Any chance that you could squeeze a bit down line as I am farting about with the feed nuts on a Super7B which had a gear box full of mahogany dust on purchase? The rest is quite unprintable. Again, my thanks- meanwhile, back to the shed! Norman >Tony, Many thanks from the once capital of the innovative industry. > [quoted text clipped - 6 lines] > >Norman Just get a new pair from Myfords, they're not expensive. Mark Rand RTFM >Any chance that you could squeeze a bit down line Its not a terribly divisible product unfortunately - it comes in a tin with a separate bottle of hardener so its a bit of an all or nothing job - and for what I paid for this lot (about 50 squid when you add all the release agent paraphenalia, cartridges so that you can inject the stuff, VAT, etc. etc.) you could probably get some shiny new nuts from Myfraud & still have change for a couple of pints to wash the mahogany dust out of your system. Regards, Tony The feed nuts are only the first part. I am now setting up dial assemblies which are somewhat( geez) worn. And then there are the gibs which will go onto the little Clarkson and so ad infinitum.And then there is this Cervantes fellow who wrote " Patience, fleas, the night is long" if you know what I mean. Like the old maxim about having a spare clip of ammo.- Prediction is very difficult especially about the future. Thanks again Norm > Hi, > [quoted text clipped - 15 lines] > > Many thanks, My homebrew hot wire foam cutter uses leaded bronze bushes (mounted in ali box sections cut from a builders level bought in a sale) sliding on plain ordinary unground stainless steel rods - I didn't want to use ms or cast iron for the rods in order to avoid any possible corrosion problems, although the frame is 18x18 mm MS box section. I did polish the rods a bit, by hand, but I don't know that it mattered. Uses B+Q 6x1 mm threaded rods for leadscrews, and four small very cheap 200-step steppers directly connected to the screws. Uses the bearings in the motors for reference points, with just a loose hole in the box section for location at the other end, though I once planned to fit a sleeve. If there is any play, I can't see it. ~1310 mm long with two 240x120 mm X-Y areas, used for cutting wings from 1220 mm long foam blocks. As accurate as I could wish, repeatable to within a thou or better :). Runs on a BBC micro though, so it's a hassle to input wing sections. The forces on a router will be quite a bit larger than on a hotwire cutter, but I'd guess that wouldn't cause any real problems. I'd use thicker rods - mine are only 8mm, for a small router I'd go to at least 16 mm and maybe more. If you want real rigidity though, and you might, try 25/30 mm cast iron bar - College Engineering sell it "proof machined", but it ain't cheap. The used front suspension struts Tom mentioned also sound interesting. But bronze will do for bearings. SignaturePeter Fairbrother |
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