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Let's mod a PL-41 !

Update on PL-41 thrustplate.

I have a line on 7/8" OD, 1/8" thick teflon disks that would fit perfectly (20 for $25), but further research (I'm an anally retentive engineer) has revealed that Teflon is not suited for use as a thrust bearing (too soft).

As for Delrin, it's defininitely a suitable material, but AFAIK the disks need to be machined from 7/8" Delrin bar stock. I got a price quote from a local machine shop. For 20, it's $4.50 apiece. For a dozen, it's $6 apiece. I'm going to poke around a bit more and I'll keep you posted on this thread.

From the picture in the link I attached previously, it appears that the original plastic thrust pad had two thin aluminum disks under it. Reading further in the thread, a fellow who had a Delrin thrust pad made (~$10-12 at a machine shop) in the thickness of the original (.083") and installed on top of the two original aluminum disks (in an oil bath) had the entire bearing rotate in the housing (uncool) and ended up putting a rubber O-ring underneath the Delrin pad instead of the 2 aluminum disks. He further recommended simply cutting the Delrin a little thicker and not using the aluminum disks or the O-ring. Accordingly, I plan to simply have the disks cut to 1/8" thickness.

Whatever route we take, the new thrust bearing will probably be dimensionally different than the effective depth of the worn/broken up thrust bearing you have in your TT. Accordingly, after installation a quick reset of VTA is probably advisable.

Any thoughts?
 
finnbow said:
Update on PL-41 thrustplate.

I have a line on 7/8" OD, 1/8" thick teflon disks that would fit perfectly (20 for $25), but further research (I'm an anally retentive engineer) has revealed that Teflon is not suited for use as a thrust bearing (too soft).

As for Delrin, it's defininitely a suitable material, but AFAIK the disks need to be machined from 7/8" Delrin bar stock. I got a price quote from a local machine shop. For 20, it's $4.50 apiece. For a dozen, it's $6 apiece. I'm going to poke around a bit more and I'll keep you posted on this thread.

From the picture in the link I attached previously, it appears that the original plastic thrust pad had two thin aluminum disks under it. Reading further in the thread, a fellow who had a Delrin thrust pad made (~$10-12 at a machine shop) in the thickness of the original (.083") and installed on top of the two original aluminum disks (in an oil bath) had the entire bearing rotate in the housing (uncool) and ended up putting a rubber O-ring underneath the Delrin pad instead of the 2 aluminum disks. He further recommended simply cutting the Delrin a little thicker and not using the aluminum disks or the O-ring. Accordingly, I plan to simply have the disks cut to 1/8" thickness.

Whatever route we take, the new thrust bearing will probably be dimensionally different than the effective depth of the worn/broken up thrust bearing you have in your TT. Accordingly, after installation a quick reset of VTA is probably advisable.

Any thoughts?
Click to expand...

Just for confirmation, cutting the Delrin stock at 1/8th thickness will negate the need to use the two aluminum discs or an O-ring. Is this correct?
 
Last edited:
Mark Walters said:
Just for confirmation, cutting the Deltin stock at 1/8th thickness will negate the need to use the two aluminum discs or an O-ring. Is this correct?
Click to expand...

Yep. That's the (tentative) plan. I'll open up the bearing tonight and measure the composite thickness of all three disks. I really don't think it's all too critical to match the cumulative thickness exactly as the plastic thrust pad on my TT has worn completely through and the spindle has actually worn a sizeable dimple in the top aluminum disk below it. Accordingly, my spindle is probably riding about 1/10" of an inch lower than it was when the TT was new.

As the years go by, this is compensated for by VTA adjustment whenever you mount a new cartridge.

I've been looking around a bit for someone who sells premade Delrin disks (7/8" x 1/8") as is the case with Teflon. No luck yet. I'm sure they would be much cheaper if they existed somewhere off-the-shelf.
 
I agree.

On another note, I think I am going to pull the plug and buy a Rega RB 250. I hate the idea of cutting into the deck of my PL-41, but as of now it is not even my #2 turntable. If things go south I can always use the Rega arm on my Thorens TD 145 MK II in which I already have an adapter. I have to find a machine shop that can do a precise cut on the Pioneer though. I still believe that the Rega arm will make a profound difference. I look at my Music Hall MMF 5.1 and the only part it has that is superior to the PL-41 is the arm and cart. I mean, what else could account for the superior sound?
 
Guys.... I gotta add one thing to this the 2 piece platter mat on the PL-41 Id like to find a shop that could machine off that PITA metal ring so I could use any mat I want.
My preference is a plain old Felt mat like Linn uses.....


bob
 
finnbow said:
I've been looking around a bit for someone who sells premade Delrin disks (7/8" x 1/8") as is the case with Teflon. No luck yet. I'm sure they would be much cheaper if they existed somewhere off-the-shelf.
Click to expand...

Check at your local hobby shop. Most electric radio-controlled race cars use delrin spur gears about 1/8" thick. Some older RC cars used delrin thrust bearings. Or do a search at Tower Hobbies for delrin.
 
Count me in for a Delrin thrust bearing. I found a 1-inch plastic math counter in my kids' playroom, and filed it down to a snug fit. Seems to be working, but I'd rather have the official AK PL-41 Owners' Club version.:thmbsp:
 
MrIgotNomoney said:
Guys.... I gotta add one thing to this the 2 piece platter mat on the PL-41 Id like to find a shop that could machine off that PITA metal ring so I could use any mat I want.
My preference is a plain old Felt mat like Linn uses.....


bob
Click to expand...

Herbies Way Excellent mats will make a custom one for the PL-41. So they say...
 
Dang.

Every time I think I've got a suitable tonearm candidate within reach,....
Well, you know how ebay goes.

I've posted in Bartertown some gear I'd be willing to trade or cash/trade for an arm.
 
Naptown Rob said:
Dang.

Every time I think I've got a suitable tonearm candidate within reach,....
Well, you know how ebay goes.

I've posted in Bartertown some gear I'd be willing to trade or cash/trade for an arm.
Click to expand...

Hang in there...I still may just go ahead and buy a Rega arm but I j-u-s-t
c-a-n-'t s-e-e-m t-o d-o i-t!
 
FROM THIS THREAD-

finnbow said:
I quickly roughly measured the mounting distance and effective length of the tonearm on the PL-41. The mounting distance is ~223 mm and the effective length is 237mm...
Click to expand...

FROM ANOTHER THREAD-

jbpollock said:
I made some preliminary measurments using just a cloth measuring tape which isn't so good for exact mm lengths. The distance between the center of the spindle and the center of the arm pivot is in the neighborhood of 222-224 mm and the arm mounting hole is about 22 mm. I obvioulsy need a better way for exact measures...
Click to expand...

Holst said:
You will most likely have to do some measuring yourself. That arm is, a Jelco tube with CEC bearing(s). It will likely measure out to be the same as, or very close to, a Linn type...
Click to expand...


MY QUESTION-

What's the ideal arm measurements?

Here's what's on hand-

Sumiko MMT

Sumiko FT-3.

Audioquest PT-6.

Also a Pioneer PA-1000.

The Audioquest-

Specifications
Effective length: 229mm
Overhang: 18mm
Mounting distance: 211mm
Mounting pattern: Linn type

Sumiko Premier MMT and FT-3-

Specifications
Overall length: 305mm
Effective length: 239mm
Overhang: 17.3mm
Offset angle: 23.1 degrees
Mounting distance: 221.7mm
Maximum backswing: 64mm
Cartridge weight range: standard up to 8g, extra weight 8-14g

Pioneer PA-1000-

Specifications
Type: static balance type, s-shaped, carbon fibre arm
Effective length: 237mm
Overhang: 15mm
Mounting distance: 222mm
Mounting hole: 21mm
Tracking force: 0-3g
Height range: 40-56mm
Headshell: plug-in type
Cartridge weight: 4-15g
Subfunctions: anti-skating force control, arm elevation device, arm height adjusting device
 
Pioneer PA-1000-

Specifications
Type: static balance type, s-shaped, carbon fibre arm
Effective length: 237mm
Overhang: 15mm
Mounting distance: 222mm
Mounting hole: 21mm
Tracking force: 0-3g
Height range: 40-56mm
Headshell: plug-in type
Cartridge weight: 4-15g
Subfunctions: anti-skating force control, arm elevation device, arm height adjusting device
Click to expand...

This one seems like a ideal fit, IMHO.
 
I imagine one could purchase a small piece, say 3" by 4" or so, of 1/8" carbon fibre board on the cheap and mount it to the top plate via four allen bolts- cut out the original mounting hole larger, and this would allow numerous arms to be swapped in or out via four bolts and a couple of mounting plates.

The top mount looks like you could self-tap the four holes. The carbon Fibre plate would be quite strong and not add any real significant height to the deck.

An aftermarket arm would allow a nice VTA range anyhow, and this thrust bearing would also work in harmony with the slight increase in board height too.
 
Mark Walters said:
Hey Deli, do I need to send you my PL-41 too?!!
Click to expand...


I am finishing up another fella's Pioneer arm mount as we speak, and have all the goodies in for the Sony.


I decided to go with thin sheets of carbon fibre for the Sony and build my own RCA plate- I just couldn't get a proper wall-mount plate with snap-in RCAs to fit quite right.

The sheets are marked for cutting.:thmbsp:
 
thedelihaus said:
I am finishing up another fella's Pioneer arm mount as we speak, and have all the goodies in for the Sony.


I decided to go with thin sheets of carbon fibre for the Sony and build my own RCA plate- I just couldn't get a proper wall-mount plate with snap-in RCAs to fit quite right.

The sheets are marked for cutting.:thmbsp:
Click to expand...

I am patiently waiting for your masterpiece. What do you think about this PL-41 business? I do have an adapter for my Thorens that will allow use of a Rega arm-straight bolt in. Maybe it would be adaptable to my Pioneer. When I get home I will take some pics of it and post.
 
Both the PA-1000 & the MMT are looking interesting to me. Discuss amongst yourselves.

The donor of The Patient is back home, so surgery now awaits...
 
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