I have a few questions and hope to get much feedback on this. This is using borosilicate glass tubing (10mm diameter) and 7.5mm diameter graphite tubing (from an arrow)...
1) How long are you making your tonearm from counter weight to tip of cartridge mount?
2) What cartridge are you using and what do you have it tracking at?
3) What type of stylus do you have (shape)?
4) Do you have your support perfectly level or is it tilted slightly inward?
5) Do you have any friction issues with the glass rod and 4 bearings?
6) What is the overall weight of your arm including cartridge and counter weight?
Here is the reason that I am asking these questions... a friend of mine built the tonearm but he made the tube from the cart to the cartridge about 6" long. In order to avoid tracking issues, he ended up having to cut the rod and install a flexible (left to right only, not up and down) piece because as the stylus tracked in the groove of the record, it would try to move the entire fixture back and forth. Unless he was tracking with a weight of over 3g, he would get skipping. Even now if the stylus were to hit a dust spec in the groove, it will skip at the max allowed weight for the cartridge.
For mine I am going to make the arm 2.5" and see what difference that makes compared to his. I think I have talked him into redesigning his to a much shorter wand length, so we will see what impact that has.
I appreciate as much input on this as possible from as many folks who have built the linear arm as possible. Just trying to collect data.
1) How long are you making your tonearm from counter weight to tip of cartridge mount?
2) What cartridge are you using and what do you have it tracking at?
3) What type of stylus do you have (shape)?
4) Do you have your support perfectly level or is it tilted slightly inward?
5) Do you have any friction issues with the glass rod and 4 bearings?
6) What is the overall weight of your arm including cartridge and counter weight?
Here is the reason that I am asking these questions... a friend of mine built the tonearm but he made the tube from the cart to the cartridge about 6" long. In order to avoid tracking issues, he ended up having to cut the rod and install a flexible (left to right only, not up and down) piece because as the stylus tracked in the groove of the record, it would try to move the entire fixture back and forth. Unless he was tracking with a weight of over 3g, he would get skipping. Even now if the stylus were to hit a dust spec in the groove, it will skip at the max allowed weight for the cartridge.
For mine I am going to make the arm 2.5" and see what difference that makes compared to his. I think I have talked him into redesigning his to a much shorter wand length, so we will see what impact that has.
I appreciate as much input on this as possible from as many folks who have built the linear arm as possible. Just trying to collect data.
My arm <25g with cartridge. I use a Denon 103r about 1.8gm tracking. 2.3" from tip of stylus to pivot. Arm is a little longer than that for counter weight. Length for counter weight wasn't critical for me, probably could be about 1.5 inches. No friction issues. Glass is as level as I can make it.
I used hard maple to support the glass rod. Basically because I had it. Still sounds great!
I used hard maple to support the glass rod. Basically because I had it. Still sounds great!
Attachments
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A tip,
3" is pushing the utmost limit here, 6" is overtaking it. Why make the arm longer than the sx74 neumann cutterhead anyways?. As designed tracking is Superb when level, the longer you make the arm the more you make the side forces on the stylus larger, there is a method to the madness here. I'll divulge another secret in this design and why this length was ultimately adhered to by me. Once tracking force is set, follow the sra of the cantilever, assume this line keeps coming out of the back of the cartridge, it should intersect around the center of the glass tube
, think physics here.
Colin
3" is pushing the utmost limit here, 6" is overtaking it. Why make the arm longer than the sx74 neumann cutterhead anyways?. As designed tracking is Superb when level, the longer you make the arm the more you make the side forces on the stylus larger, there is a method to the madness here. I'll divulge another secret in this design and why this length was ultimately adhered to by me. Once tracking force is set, follow the sra of the cantilever, assume this line keeps coming out of the back of the cartridge, it should intersect around the center of the glass tube
, think physics here.Colin
A tip,
I'll divulge another secret in this design and why this length was ultimately adhered to by me. Once tracking force is set, follow the sra of the cantilever, assume this line keeps coming out of the back of the cartridge, it should intersect around the center of the glass tube
May not always be possible without some convoluted design depending on cartridge. Denon 103 won't is a good case in point. I am sure other will and it is a good idea.
Still sounds great with it being off axis though
Vinuhl.addict, Kffern:
There would be no difference between a tungsten carbide rod and a glass or ceramic tube IF the tubes were ground and polished as well as the carbide rod---but they are not--they are extruded and cannot be as round or straight or have as few of flaws as a ground and polished carbide rod. Any material that is properly ground and polished would be better then same material that is extruded.
It is almost impossible to feel if a tube in your hand is perfectly round or find micro-flaws with the naked eye. I feel it is critical to a smooth and consistent movement of the carriage and the ability of a cartridge to track in a flawless manner.
I KNOW my carbide rod is near perfect in every dimension---can anybody using a common glass or plastic tube say the same ? No. Why introduce a POSSIBLE problem if you do not have to. To me it is called peace of mind. My logic may be overkill for this design--but so what. I choose not to introduce any possibility of problems pertaining to the carriage support. I know you can get good results from common glass tubes---but why settle for just good. If good is good enough then I say great and use it as is.
I am sure some folks building this arm have had unexplained tracking problems, uneven carriage movement etc. even though they made a proper carriage. The problem may be a flawed carriage support. Just my 2 cents.
Joe
There would be no difference between a tungsten carbide rod and a glass or ceramic tube IF the tubes were ground and polished as well as the carbide rod---but they are not--they are extruded and cannot be as round or straight or have as few of flaws as a ground and polished carbide rod. Any material that is properly ground and polished would be better then same material that is extruded.
It is almost impossible to feel if a tube in your hand is perfectly round or find micro-flaws with the naked eye. I feel it is critical to a smooth and consistent movement of the carriage and the ability of a cartridge to track in a flawless manner.
I KNOW my carbide rod is near perfect in every dimension---can anybody using a common glass or plastic tube say the same ? No. Why introduce a POSSIBLE problem if you do not have to. To me it is called peace of mind. My logic may be overkill for this design--but so what. I choose not to introduce any possibility of problems pertaining to the carriage support. I know you can get good results from common glass tubes---but why settle for just good. If good is good enough then I say great and use it as is.
I am sure some folks building this arm have had unexplained tracking problems, uneven carriage movement etc. even though they made a proper carriage. The problem may be a flawed carriage support. Just my 2 cents.
Joe
Gang ... I'm sure this is in here somewhere, but worth repeating. Was the final sell to me.
DIY Linear Tracking Tonearm by kiirojbl 5 - YouTube There are more of his vids.
Zene
DIY Linear Tracking Tonearm by kiirojbl 5 - YouTube There are more of his vids.
Zene
Great little video. Using the linear ball bearings does have its problems with dust. The smoothness of the rod was also critical, as I suppose is the diameter.
There seems a lot of concern about the perfection of the straightness of the rod. I have no doubt that a machined tungsten rod will be more perfect than a glass rod in terms of it being straight.
However, if you were to look at the surface of a highly polished tungsten rod with a scanning electron microscope, and a fire polished glass tube, the glass tube may well be superior.
If you were to slide a rod made from the same steel as the ball bearing outer race, over a glass rod, or over a tungsten rode, which would have the lower friction?
I suspect that the friction of contact points might be more significant than the straightness of the rod.
Another point to consider is which surface is less affected by dust sticking to it.
Lets try a little science here.
There seems a lot of concern about the perfection of the straightness of the rod. I have no doubt that a machined tungsten rod will be more perfect than a glass rod in terms of it being straight.
However, if you were to look at the surface of a highly polished tungsten rod with a scanning electron microscope, and a fire polished glass tube, the glass tube may well be superior.
If you were to slide a rod made from the same steel as the ball bearing outer race, over a glass rod, or over a tungsten rode, which would have the lower friction?
I suspect that the friction of contact points might be more significant than the straightness of the rod.
Another point to consider is which surface is less affected by dust sticking to it.
Lets try a little science here.
Hi SGregory...
Have you found out any enhancements for the values in the drawings or are they still valid?
Brgds
Have mine up and running since last night.
I de-greased my bearings and they move like a champ
across the glass tube. Total weight of arm...without cartridge...
came in close to 23gms.
My arm is as level as I can make it, but I'm going to
fiddle with it and the counter weight over the next few days.
I was amazed that it "just worked" right out of the gate.
I picked a couple of albums I dont care for...poor recordings...for
the first spins, ones I could loose. I also picked an old cartridge
AT13 Ea for the same reason, expendable.
When I was confident I hadn't built a wrecking machine, I played
a well recorded album.
My room is set up for critical listening, fully treated,
big open baffle speakers, one center chair.
With that old Audio Technica cartridge I was just gobsmacked
Wasnt expecting that.....wow.
This is really a nice piece.
Hunting for a proper cartridge now.
I de-greased my bearings and they move like a champ
across the glass tube. Total weight of arm...without cartridge...
came in close to 23gms.
My arm is as level as I can make it, but I'm going to
fiddle with it and the counter weight over the next few days.
I was amazed that it "just worked" right out of the gate.
I picked a couple of albums I dont care for...poor recordings...for
the first spins, ones I could loose. I also picked an old cartridge
AT13 Ea for the same reason, expendable.
When I was confident I hadn't built a wrecking machine, I played
a well recorded album.
My room is set up for critical listening, fully treated,
big open baffle speakers, one center chair.
With that old Audio Technica cartridge I was just gobsmacked
Wasnt expecting that.....wow.
This is really a nice piece.
Hunting for a proper cartridge now.
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Pickering XLZ 7500S
I went to the XLZ 7500S Pickering cart with this arm ( no fear ) .. tracking force at 1.75 Gram .. what a great little sleeper this amazing cart . hooked it up with a battery feed SK146 junction fet prepre .. stunning believe me !
Also fiddled a bit more with the wiring and decided to try an extremely thin HF copper litze . almost undoable with bare eyes .. but I succeeded .. as most the times
What a JOY
Paul
I went to the XLZ 7500S Pickering cart with this arm ( no fear ) .. tracking force at 1.75 Gram .. what a great little sleeper this amazing cart . hooked it up with a battery feed SK146 junction fet prepre .. stunning believe me !
Also fiddled a bit more with the wiring and decided to try an extremely thin HF copper litze . almost undoable with bare eyes .. but I succeeded .. as most the times
What a JOY
Paul
Attachments
Thanks Scott.
I recalculated them to metric and yes - you are using a thicker rod so some values needs to be altered for a 10mm one.
Brgds
Hi Chris.
Could you give us a shot on the leveling apparatus from beneath showing whats under the top circular shim? How did you fasten it to the tubeholder and the bottomplate?
Brgds
I was going to refrain from commenting on this issue, but somehow I can't. Why are you so firmly supporting your carbide rod over glass but not a mention of bearing condition? From my own observation and only one other member's stated experience, the corners/edges of the commonly used model car bearings look like a ploughed field. This is a problem orders of magnitude greater (imho) than the glass/carbide issue. In evaluating a bunch (4) of cartridges on my glass tube highly polished bearing edges LT arm, much to my amazement the need for a level arm tube has virtually disappeared. I'm getting the same sound and no skips or unwanted behavior with somewhere near 10 to 12 degrees +/- deviation from level. That doesn't mean I'll use that kind of slope.
I am convinced that given the quality of laboratory borosilicate glass tube, the solution to problems you are guarding against will be found elsewhere. Then, maybe, we can improve performance with the carbide rod. I do think that the steel on steel friction will prove the steel on glass friction to be the winner.
Rgds,
BillG
Cornelis Spronk:
The material I am referring to is tungsten carbide and not tungsten. Tungsten carbide is much harder although a ground and polished tungsten rod would work for this arm.
An electron microscope ( depending on magnification ) could make the smoothest surface look like the surface of the moon. However your point is well taken. If I could get some ground and polished ceramic or glass tubing I would use it without hesitation.
As to the friction difference between a properly ground and polished carbide rod, tool steel rod, or glass rod I doubt there would be much difference as it pertains to this arm design. I would not use steel however because if is magnetic. Dust is an issue with this arm for sure but I do not know which material will attract or hold dust more.
Bgruhn:
You are absolutely correct about the condition of the bearings contact points. At least you examined to bearings to spot the flaws. How many here blindly accept that the bearing are good as is ? The bearing contact points must be polished to the highest degree possible for best performance.
Laboratory grade glass usually refers to the purity of the glass and not ' perfection " of its dimensions, unless specified.
Like building a house, the better foundation the better. The foundation in this arms design is the carriage support. Your "perfectly" polished bearings should roll on a "perfectly" straight, round and flawless support IMHO. After you have completed all these tasks and if you have any tracking issues you can look elsewhere for the problem.
Joe
The material I am referring to is tungsten carbide and not tungsten. Tungsten carbide is much harder although a ground and polished tungsten rod would work for this arm.
An electron microscope ( depending on magnification ) could make the smoothest surface look like the surface of the moon. However your point is well taken. If I could get some ground and polished ceramic or glass tubing I would use it without hesitation.
As to the friction difference between a properly ground and polished carbide rod, tool steel rod, or glass rod I doubt there would be much difference as it pertains to this arm design. I would not use steel however because if is magnetic. Dust is an issue with this arm for sure but I do not know which material will attract or hold dust more.
Bgruhn:
You are absolutely correct about the condition of the bearings contact points. At least you examined to bearings to spot the flaws. How many here blindly accept that the bearing are good as is ? The bearing contact points must be polished to the highest degree possible for best performance.
Laboratory grade glass usually refers to the purity of the glass and not ' perfection " of its dimensions, unless specified.
Like building a house, the better foundation the better. The foundation in this arms design is the carriage support. Your "perfectly" polished bearings should roll on a "perfectly" straight, round and flawless support IMHO. After you have completed all these tasks and if you have any tracking issues you can look elsewhere for the problem.
Joe
Joe,
So in other words tungsten carbide is the black gates to the run of the mill low esr caps equivalent?. Though I find it highly premature to say that with Boro.glass it's only "good" which tells me you haven't built this arm as is. I've had no tracking issue unless the tube levelling is off and only on radically off center pressings, once levelled its flawless. I would have never posted a half assed concept to begin with.
Colin
So in other words tungsten carbide is the black gates to the run of the mill low esr caps equivalent?. Though I find it highly premature to say that with Boro.glass it's only "good" which tells me you haven't built this arm as is. I've had no tracking issue unless the tube levelling is off and only on radically off center pressings, once levelled its flawless. I would have never posted a half assed concept to begin with
.Colin
I second the point BillG reconfirmed in #854. All four of my ACER brand ceramic bearings had edges that looked unwholesome under a x10 loupe. The polishing of four of the eight edges wasn't completely easy either, and took a bit of care. Really hoping that they 'work.' Again, requesting that ChrisG139 elaborate upon his adjustable mounting base for the linear tracker, as another has asked for the same too.
I'm in process of fabricating my carriage, using a balsa, fabric and epoxy composite for the "T" section. Got the idea from the stuff that was used for Corvette floorboards (balsa sandwiched between layers of glass cloth on each side). Seemingly the small square I'm working on now of the balsa composite has very little weight. Got an Easton aluminum and carbon fiber arrow for the tonearm. Glad the arrow was a damaged give-away since I was quoted $30 each, and you had to buy 12 of the model at the local archery range.
John
I'm in process of fabricating my carriage, using a balsa, fabric and epoxy composite for the "T" section. Got the idea from the stuff that was used for Corvette floorboards (balsa sandwiched between layers of glass cloth on each side). Seemingly the small square I'm working on now of the balsa composite has very little weight. Got an Easton aluminum and carbon fiber arrow for the tonearm. Glad the arrow was a damaged give-away since I was quoted $30 each, and you had to buy 12 of the model at the local archery range.
John