Niffy may be right - I could only get cheap bearings and I know that usually the cheaper the bearing - more play there is inside the bearing itself. Once two bearings are connected into a rigid system where both outer and both races are interconnected, like within a bicycle hub, then and just then they start acting and behaving predictably. Locally, of course, only really cheap small bearings are available from the shelf. I bought 10pcs of 684 bearings (4x9x4mm) for around 5€ - for comparison, only one 684 ZrO2 bearing costs around US$25-37 prior to shipping from HK.
This only means that I need to re-think the whole thing very seriously and can't just build something so sensitive by throwing part one onto the other and expect it to work as I imagine...
This only means that I need to re-think the whole thing very seriously and can't just build something so sensitive by throwing part one onto the other and expect it to work as I imagine...
Stein, Collin's sketch, way back in the thread shows the outside diameter of the brass "shim". This works out to be a real sloppy fit into the bearing inner race (bore). The bearing is loose on the shim. I simply made my solid axle to be the same diameter as the brass shim (tube). This means that the bearings (mated pairs) are not solidly connected to each other and are free to self align. I've not done a thorough analysis of how this relates to eccentricity, but I think it will show that the eccentricity of the bearings will wash out completely. Perhaps lawn mower bearings from the hardware store will not follow through. The critical parameters being the actual roundness and finish of the races on which the balls roll. The success of this arm design truly depends on loose fitting bearings and excellent surface finish of contacting surfaces. Ever wonder why cheap cameras and watches keep working in sub-zero climates whilst precision ones tend to curl up their toes and quit? Acer-racer has hybrid ceramic bearings for under USD 10 and they do ship internationally. Their bearings have been used successfully by myself and many of the other builders on this thread.
(I have no connection, financially or otherwise to that firm). Email me if you want more info, "bgruhn508@gmail.com".
Rgds,
BillG
No need to rewind the thread. Just reread the previous post. That is exactly what I said. And more!
Cheers,
BillG
Bgruhn,
The bearing arrangement is only kept apart by the round of the tube. The shim/sleeve is just slightly smaller than the 5mm bearing center and is made from brass tubing from a hobby shop and also acts as a spacer. I have used a to220 nylon insulating washer to center this sleeve and space the bearing from the polycarbonate piece. It all works together in this arrangement and helps reduce friction, it's also not machined as my goal was to see if I could do this from basic materials.
Colin
AurroraB,
Looks like I'm not the only one to misinterpret Colins explanation.
I think I do now, but have yet to implement it. My understanding of a shim or a sleeve are 2 different things and I seem to have gone off on a different tack with partial / intermittent success. I may also have dodgy bearings.
Colin, could you show us a picture of a disassembled pair of bearings and their components?
My bearings are 3mm ID and my bolts are M3 with a smooth shoulder. Could I just let them run free with a tophat on one end and and spacer and bolt on the other?
Thanks,
kffern
Hi Moray,
IIRC you actually do have a Cantus tonearm. I wonder if yours is set up far enough to do a simple test for me. If not, could you refer me to someone with a Cantus who I could ask a favor of?
With the Cantus set up, record on TT, amplifier turned on to a fairly good volume, but not screeching loud, and the stylus resting on the non-rotating record, finger tap the glass tube up close to the mounting block, then again about half way down the traverse, and last at the far end of the tube. Then report what you/they have heard. I'm looking to find out if Cantus/Bo has solved the problem of the glass track resonating with some degree of ringing at a low frequency. If no significant ringing is heard, can you surmise how it was eliminated?
On a full round tube, not slotted like Cantus employing the standard damping methods, filling with sand or non-dairy creamer powder damps high frequencies well but not the full length of the tube resonance. Mounting the tube with rubber washers on a non-contacting support rod down the middle, washers at both ends to isolate the glass tube does very little to help.
I'm wondering if the diameter of the Cantus track tube, as well as the slot for the carriage to run could have any effect, perhaps shifting the resonance out of audible range.
Rgds,
BillG
would it be possible to ............
create a place / space here , page or depot where diagram , schematics , foto , video etc. could be dropped ? so everyone can find specific info of the LT arm . Instead of going through 120 pages of text in order to trace visual arm details ? just an idea
I figure that many do find difficulties in understanding the basic details of this arm !
THX
Paul
create a place / space here , page or depot where diagram , schematics , foto , video etc. could be dropped ? so everyone can find specific info of the LT arm . Instead of going through 120 pages of text in order to trace visual arm details ? just an idea
I figure that many do find difficulties in understanding the basic details of this arm !
THX
Paul
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create a place / space here , page or depot where diagram , schematics , foto , video etc. could be dropped ? so everyone can find specific info of the LT arm . Instead of going through 120 pages of text in order to trace visual arm details ? just an idea
I figure that many do find difficulties in understanding the basic details of this arm !
THX
Paul
Such a repository could serve well. The following coments are offered in all sincerity, not directed for or against any individual(s). I recognize that English is not the first language of many of us here. I'm amazed that many non-native English speakers both read and write with far greater fluency than many of us native English speakers. My hat is off to you folks. Others of us are very poor at expressing our thoughts in a meaningful way. Still others have been tought in these modern times to read rapidly and without any great comprehension. Glance at it and get the general idea. This does not work very well with technical writing. Others, myself included, get wordy and introduce too many thoughts or concepts in a given piece.
One of my pet peeves is the written sample that introduces a thought or answers a question so ambiguously that the reader has no way to determine just what the writer is trying to convey. Another is the chap who asks 2 questions and a reader who dutifuly answers, but only one of the 2 questions. Rest assured the answer will be for the least important question. The important one lost forever!
COMMUNICATING is the name of the game. Before you hit the Submit Reply or Post button, read the message a few times carefully. Does it actually say what you are trying to convey? If a post is ambiguously worded, write the guy back and say, I can take this as A or B. Please explain. But also look at what has been said and if you understand the theory behind it can you reliably determine the correct answer even before asking.
If we all can do our best to communicate in a meaningful manner, this will raise reputation of this forum whole levels higher. It is work, but well worth the effort. We are not doing it often enough now (eg. I just had to reword this sentence 3 times to get it right!)
Time to get off the soap box,
BillG
I did just that last night and it works a lot better. The LP I've been trialing with over the last couple of months might have a few defects by now but played another LP this morning with a couple of mistracks which corrected itself.
Using a 5mm ID bearing with the "sleeve/spacer"would make it easier to set up the bearing gap but this works with a bit of fiddling. On my 12mm glass tube a 5 to 6mm gap seems to work. Anything larger won't and anything less is too unstable.
Looking at the stylus from the front shows it to wiggle side to side quite a lot. Can't remember if it does that in a standard arm.
Does anyone else see this in their arm and am I damaging the stylus and/or LP in the long term?
I think I will experiment further with better quality bearings. There are Abec-5 to 7 steel, dry, bearings for fishing reels sold on ebay (US) for $5 to $7. Don't touch those 10 for $3 from chinese bearings. Shipping is the main cost for Australians.
Regards,
kffern
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Looks like you are making progress, good! Let's hear how you do with the fishing reel bearings. The biggest difference between ABEC 5 and 7 is dimensional tolerances. The 7 class being held tighter than the 5 class. For this application the 7 may not be as good as the 5. Remember what I recently said about dry vs thin film of light oil. Try it both ways though.
Re stylus hunting: a properly running LT of this type should exhibit no hunting. Hunting or stick-slip indicates too much friction in the system somewhere. Your axle clearance and finish could actually be giving problems. If you don't have a lathe to make nicely finished and dimensioned axles, try to find Colin's brass tube shim material and don't distort it in the cutting it to size.
Are you damaging stylus or LP with excessive hunting? If not a long term condition, probably no damage, but it isn't doing any good either.
Best of luck,
BillG
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BILLG,
So far I have had better results with dry bearings. I did try very light Wahl hair trimmer oil, WD40, and Inox (aussie version of WD40 with lanolin).
Of course this was with the inner races locked by a 3.5mm tube so will try again. There may have been other variables which are difficult to seperate.
Does anyone know what diameter tube and bearing size Cantus uses?
I'm considering using perspex tube on another TT.
kffern
So far I have had better results with dry bearings. I did try very light Wahl hair trimmer oil, WD40, and Inox (aussie version of WD40 with lanolin).
Of course this was with the inner races locked by a 3.5mm tube so will try again. There may have been other variables which are difficult to seperate.
Does anyone know what diameter tube and bearing size Cantus uses?
I'm considering using perspex tube on another TT.
kffern
The Cantus uses a pyrex tube which is 1/2"OD. with 9/32" ID. I just measured mine (Cantus) with a cheap vernier caliper. Plastic tube is not your best choice but you can probably get it to it work. I think that either Bill or Dtut built one with plastic hot water plumbing pipe, but the idea is to have two very hard surfaces so the bearing surface and the tube are very hard in order to reduce friction as much as possible like a train does with its steel wheels and rails. The harder the material used the lower the friction will be. It is a good idea to design so the ware that takes place is such that it will be cheaper and or easier to replace part will be the part which does the wearing out and so the softer of the two materials used. In the case of the Cantus the bearing surface will wear before the glass tube will.
I suspect that WD40 may contain air drying oils I have found it gums up over time and freeze the bearing so it is not a good choice and I would recommend that you wash it out of your bearings. Best regards Moray James.
Mohs Scale of Hardness
I suspect that WD40 may contain air drying oils I have found it gums up over time and freeze the bearing so it is not a good choice and I would recommend that you wash it out of your bearings. Best regards Moray James.
Mohs Scale of Hardness
Thanks Moray,
What size are the bearings?
I tried lubricating the bearings because there were posts recommending it, although I now realise a lot of the posters haven't even got a prototype going or haven't shown any results. Never did like WD40 either. The bearings were all washed out with a final rinse with ethyl alchohol. I feel dry is best but am willing to experiment. I've seen some bearing lubes in syringes at the hobby shop which look very light.
Kffern
What size are the bearings?
I tried lubricating the bearings because there were posts recommending it, although I now realise a lot of the posters haven't even got a prototype going or haven't shown any results. Never did like WD40 either. The bearings were all washed out with a final rinse with ethyl alchohol. I feel dry is best but am willing to experiment. I've seen some bearing lubes in syringes at the hobby shop which look very light.
Kffern
Concerning the bearing arrangement:
It has come to light how important this is, which doing many trial and errors wholeheartedly agree. This brass shim/sleeve is 4.76mm od, cut and filed to a length of 11mm, the bearings are 9mm, with an inner diameter of 5mm, and a width of 3mm. If a 10mm tube is used this leaves approximately a 5mm bearing spacing, the bearings with all due respect must be sloppy on the sleeve. It is a system which works together, and relies on some pretty firm adhesion to what I Have offered to give the results I consistently get ). This is an arm for mid to low compliance cartridges, there should be little to no needle wiggle on eccentric records. No specialty parts should be needed, no space material bearings for great results, oh yes, and don't clean them, and it you do, re lube then and keep the dust covers on.
Colin
It has come to light how important this is, which doing many trial and errors wholeheartedly agree. This brass shim/sleeve is 4.76mm od, cut and filed to a length of 11mm, the bearings are 9mm, with an inner diameter of 5mm, and a width of 3mm. If a 10mm tube is used this leaves approximately a 5mm bearing spacing, the bearings with all due respect must be sloppy on the sleeve. It is a system which works together, and relies on some pretty firm adhesion to what I Have offered to give the results I consistently get ). This is an arm for mid to low compliance cartridges, there should be little to no needle wiggle on eccentric records. No specialty parts should be needed, no space material bearings for great results, oh yes, and don't clean them, and it you do, re lube then and keep the dust covers on.
Colin
Hi Colin,
Shouldn't that depend on the original lubricant in the bearing. The sealed bearings I bought from RS supplies here ($9 each, non ABEC rated) had grease in them. Even after soaking in WD40 there was still clumps of white (lithium) grease in them when I eventually removed the shields.
After months of looking through bearing websites, there are dry (usually ABEC 5 and up), oil and grease lubricated bearings. Some even specify which race they are designed to spin on. You may have lucked out with a light oiled bearing?
Regards,
Kffern
Kffern: you are most welcome...
The Cantus bearings are 1/4" in dia. and are 1/16" thick. Thee bearings are dry and 100% clean of lubricant. II doubt that alcohol is a sufficient solvent to dissolve grease or other petroleum based lubricants. Gasoline or Naphtha (white gas) or a volatile degreaser like break cleaner. Hole this is of interest and helps. Best regards Moray James.
The Cantus bearings are 1/4" in dia. and are 1/16" thick. Thee bearings are dry and 100% clean of lubricant. II doubt that alcohol is a sufficient solvent to dissolve grease or other petroleum based lubricants. Gasoline or Naphtha (white gas) or a volatile degreaser like break cleaner. Hole this is of interest and helps. Best regards Moray James.