Several pages back it was suggested that running ball races on angle alloy was a no no as the material was too soft to provide the low friction/rolling resistance we were trying to achieve. Now I see this is being used with the ball type track with excellent results. The point of contact with the edge of a ball race would seem to me to be similar to the point of contact with a 10mm ball. Am I missing something here ?
Graham.
Graham.
Hi Colin and Graham
I use a protractor to ensure top and bottom rails are parallel but also you will note that I have used 'O-rings' to damp both rails. These are horizontal on both the bottom face of the top rail and on the top face of the bottom rail. It is therefore easy to ensure they are parallel by sight.
Re. angle alloy-this format is the best I've had so far. I missed the comment about the angle being too soft. Did the contributor actually build an arm using it. I can state that my version performs flawlessly.
Regards
chris
I use a protractor to ensure top and bottom rails are parallel but also you will note that I have used 'O-rings' to damp both rails. These are horizontal on both the bottom face of the top rail and on the top face of the bottom rail. It is therefore easy to ensure they are parallel by sight.
Re. angle alloy-this format is the best I've had so far. I missed the comment about the angle being too soft. Did the contributor actually build an arm using it. I can state that my version performs flawlessly.
Regards
chris
Hi Chris,
The reason I ask is that in my trials thus far I have found some resistance however minute that doesn't always settle precisely to original tangent set. Because it allows another variable to swing out of tangent, whereas even an air bearing won't allow this. The most important bit is the tangent, of course the short arm comes an easy second. I'm not talking a wide variation but enough to make it large enough by the end of side on an lp.
Colin
The reason I ask is that in my trials thus far I have found some resistance however minute that doesn't always settle precisely to original tangent set. Because it allows another variable to swing out of tangent, whereas even an air bearing won't allow this. The most important bit is the tangent, of course the short arm comes an easy second. I'm not talking a wide variation but enough to make it large enough by the end of side on an lp.
Colin
Hi Colin
I've examined the two rails at start and end of lp. Perfectly parallel at start and perfectly parallel at end. Therefore I am not experiencing the arm moving away from tangent. Have you just done a mock-up or a working piece of kit? I'm reporting my experiences as I have found them in a real situation-tracking an lp-and it works. Can't say any more really......
Regards
Chris
I've examined the two rails at start and end of lp. Perfectly parallel at start and perfectly parallel at end. Therefore I am not experiencing the arm moving away from tangent. Have you just done a mock-up or a working piece of kit? I'm reporting my experiences as I have found them in a real situation-tracking an lp-and it works. Can't say any more really......
Regards
Chris
Hi Colin - ChrisG - et al,
Been thinking about making an LT with an added vertical pivot for ages. The 4 glass tubes with 2 roller balls has been working so well I haven't gotten a round toit until your experiment ChrisG. Well over the past couple of days I did it. It works remarkably well and seems to solve some very minor warp wow I think (not sure) I am having with the 4 tube roller ball model. I'm going to use it for a few weeks and then go back to the model without the added pivot to see/hear if there is any difference.
So far the double pivot model seems to have somewhat greater sensitivity to musical dynamics. Otherwise the two are about par. The vertical resistance is essentialy nil. I've used some 5mm OD precision ball bearings from my clock supplier. Used them as supplied, don't know if they are lubed or dry. Built a new top rail with 10mm glass tube. attached a simple frame from narrow brass brass strips about a mm thick and attached it to the glass rail with the arm wand and bearing assembly fastened to the bottom of the frame. See the pic for details. Needing an arm wand I made a new one using 1/4" (~6.5mm od) soft Aluminum tube from the hobby shop and available scraps. Tried it with no internal damping but it really needed something so I filled it with fine dry sand which tamed it well and it sounds real nice. Swapped over the ADC XLM cart and set it up. Since I was making a new carriage only, all that was needed was to slip it onto the lower rali and adjust. Now to use it some more.
Chris, I like the idea of the Aluminum angle in the upside down configuration. That should make for a less accident prone assembly. I do question the use of aluminum angle. It may work well at the start but I think the balls will wear a groove in the track. Back when I was building LT arms with window glass tracks, id did see the start of wear lines in the glas which was far harder and smoother than aluminum angle. So beware. I think you might find even better performance if you lined the angle with glass. I wonder if there is the equivalent of window glass in borosilicate glass, microscope glass perhaps? Will have to check that out.
Colin, I think that the rigidity of the single pivot model is being compromised by the dual pivot. Unless moving the vertical pivot to centerline of the wand realy shows clearly reduced warp wow, I think I feel "Iffy" about that second pivot system flapping about. Time will tell. We seem to be moving counter to everything we have been preaching with recent developments or am I imagining it all?
Rgds,
BillG
Plz ignore .txt attachment I. I was trying to attach a pic.
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bgruhn:
Look on ebay under " carbide blank " and there are various sizes of carbide flat stock you could use to eliminate the wear caused buy the hard steel ball, just glue them to the inside of your aluminum angle. You can also get precision carbide balls any size you want if you want to get fancy.
Look on ebay under " carbide blank " and there are various sizes of carbide flat stock you could use to eliminate the wear caused buy the hard steel ball, just glue them to the inside of your aluminum angle. You can also get precision carbide balls any size you want if you want to get fancy.
Bill,
Still a firm believer in rigid as possible here, from an engineering standpoint by adding another pivot in the fashion here we go against all those years of work in tonearm design. I'm sure that those hi end manufacturers searching out high spec bearings do so for sound reasons. But not to say that people don't at times prefer a unipivot style, which isn't as rigid or stable but seems to lend a smoothness to the sound.
Colin
Still a firm believer in rigid as possible here, from an engineering standpoint by adding another pivot in the fashion here we go against all those years of work in tonearm design. I'm sure that those hi end manufacturers searching out high spec bearings do so for sound reasons. But not to say that people don't at times prefer a unipivot style, which isn't as rigid or stable but seems to lend a smoothness to the sound.
Colin
I didn't polish mine and the arm worked perfectly from the off. Colin-I too am a firm believer in rigidity and hence was taking a punt with my latest design and always thought that it wouldn't work. No-one was more surprised than me when I discovered it did work-and very well too.
I'll keep everyone informed as to how things develop further.
Regards
Chris
I'll keep everyone informed as to how things develop further.
Regards
Chris
I did not polish mine neither, in my case the material (antenna rods) is coated with chrome (I think) and is very smooth so no need to do anything else just a little cleaning with cotton. why bother with a material that is "raw" or not finished unless you don't have an option of a suited material (really?)
mortron & others :
The chances of you getting 2 pairs of straight off the shelf glass rods / tubes is VERY slim to none. Polishing may help if you can verify that the rods are not bent and free of surface flaws and most people do not have the measuring equipment and or knowledge of using such equipment. Off the shelf glass rods and tubes are not perfectly round. straight, or free of flaws because they do not have be for the purpose they were designed. Glass makers are not going to spend time, money to put a boiler sight glass tube or run of the mill glass rods on a million dollar plus center less diamond grinder UNLESS YOU PAY FOR IT. I can not over state the importance of the quality of the rods / tubes that you use as they are just as important as the quality of the bearing you use. Try using linear bearing rod stock ( hardened and ground ) or precision machined aluminum rod that has been hard anodized. If you can find or have made precision ground glass tube or rod, that would be near perfect. The bottom line is that your rods / tubes need to have similar precision as the ball bearing used to gain the full potential of this arm.
And if you are looking for proof, you will notice that most of the arms here and on other linear arm construction threads will only work well with certain cartridges. If the arms geometry, bearing ( which includes the rods /tubes ) and alignment of all components were near perfect you should be able to use ANY cartridge to accurately trace the LP grove without noise, skipping, or destroying the cantilever. You have control of the arm geometry, bearing quality, so the only fly in the ointment IMHO is the quality of the rods / tubes being used and that component seems to be mostly overlooked.
Yes, this is an excellent arm, not too difficult to make, and can put to shame sonically many of the expensive pivoting tonearms out there. My hat if off to Colin and others for their design, hard work, time, and effort.
Please do not take any of my comments as a put down to anybody constructing and kindly explaining their construction ideas on this thread or anywhere else, we all benefit from everybody's time, effort and input.
The chances of you getting 2 pairs of straight off the shelf glass rods / tubes is VERY slim to none. Polishing may help if you can verify that the rods are not bent and free of surface flaws and most people do not have the measuring equipment and or knowledge of using such equipment. Off the shelf glass rods and tubes are not perfectly round. straight, or free of flaws because they do not have be for the purpose they were designed. Glass makers are not going to spend time, money to put a boiler sight glass tube or run of the mill glass rods on a million dollar plus center less diamond grinder UNLESS YOU PAY FOR IT. I can not over state the importance of the quality of the rods / tubes that you use as they are just as important as the quality of the bearing you use. Try using linear bearing rod stock ( hardened and ground ) or precision machined aluminum rod that has been hard anodized. If you can find or have made precision ground glass tube or rod, that would be near perfect. The bottom line is that your rods / tubes need to have similar precision as the ball bearing used to gain the full potential of this arm.
And if you are looking for proof, you will notice that most of the arms here and on other linear arm construction threads will only work well with certain cartridges. If the arms geometry, bearing ( which includes the rods /tubes ) and alignment of all components were near perfect you should be able to use ANY cartridge to accurately trace the LP grove without noise, skipping, or destroying the cantilever. You have control of the arm geometry, bearing quality, so the only fly in the ointment IMHO is the quality of the rods / tubes being used and that component seems to be mostly overlooked.
Yes, this is an excellent arm, not too difficult to make, and can put to shame sonically many of the expensive pivoting tonearms out there. My hat if off to Colin and others for their design, hard work, time, and effort.
Please do not take any of my comments as a put down to anybody constructing and kindly explaining their construction ideas on this thread or anywhere else, we all benefit from everybody's time, effort and input.
My Latest Version!!
Hi Colin et al
I've been using my new design for around 3 weeks now:
I can report back:
Chris
Hi Colin et al
I've been using my new design for around 3 weeks now:
I can report back:
- there is no 'wobbling' movement from the upper carriage at all from the horizontal unless I physically nudge it. I have checked regularly and both upper and lower rails remain truly horizontal.
- The pivoted arm wand is doing it's job.
- The arm has performed impeccably-and so far there is no trace of the ball bearings affecting the rails-as has been suggested might happen.
- It remains one of the best performing arms I have yet made.
- Although as with Colin, I am a believer in rigidity, this design works!
- I have just received the square section for the 'straps' and will be fitting this week.
Chris
Attachments
Hi Chris,
That's the beauty of this hobby, finding what works for you
. There are a few reasons why I'll stick to the two bearing two tube design, one being simplicity, but none of it is ego,rest assured . I'm glad you are enjoyińg flawless performance, we are apparently sharing the same enjoyment but with differnt designs.
Colin
That's the beauty of this hobby, finding what works for you
. There are a few reasons why I'll stick to the two bearing two tube design, one being simplicity, but none of it is ego,rest assured . I'm glad you are enjoyińg flawless performance, we are apparently sharing the same enjoyment but with differnt designs. Colin
Tube materials
Hi there, been lurking on this and other threads regarding LT arms.
I have a question regarding tube materials.
As an ex archer I still have several arrow shafts, both of Aluminum alloy and Carbon. They are all manufactured to be consistently round and straight; in addition the better Al. tubes from Easton are of 7075-T9 alloy and are hard anodised. These are available in lengths of up to 32" and diameters from 1/4" to 23/64". The raw tubes may be a bit too resonant, but this is easily subued by filling with either sand (for the lower tubes) or foam (lighter for the upper tubes.)
The use of these as tube material and silicon nitride balls would seem to be about as good as it gets, unless I'm missing something.
Any thoughts
Hi there, been lurking on this and other threads regarding LT arms.
I have a question regarding tube materials.
As an ex archer I still have several arrow shafts, both of Aluminum alloy and Carbon. They are all manufactured to be consistently round and straight; in addition the better Al. tubes from Easton are of 7075-T9 alloy and are hard anodised. These are available in lengths of up to 32" and diameters from 1/4" to 23/64". The raw tubes may be a bit too resonant, but this is easily subued by filling with either sand (for the lower tubes) or foam (lighter for the upper tubes.)
The use of these as tube material and silicon nitride balls would seem to be about as good as it gets, unless I'm missing something.
Any thoughts
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