Corian Turntable Fun - Page 4 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th December 2005, 03:40 AM   #31
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Amazing what a goods night rest and some aspirin can do for your attitude When I wrote the above post, I had just come in from a 2 (long) day battle and was sore and tired. I just gave my plinth the once over with a fresh outlook, and I gotta say it is nice, the brushed aluminum center rocks …definitely worth the effort.

Tonight I drilled an alignment hole in the bottom plinth, set a piece of rod in it and sat the top plinth over it. I then scribed a line around the top plinth to the bottom one. I will now remove the bulk of the excess before I set up the sanding drum. How? I’m not sure yet, bench grinder or die grinder maybe. This will save me a LOT of time on this go round.

I’ll keep ya posted,
Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 6th December 2005, 03:17 PM   #32
mpm32 is offline mpm32  United States
diyAudio Member
 
Join Date: Dec 2003
Location: New England
Why not use a router? I've used a router on aluminum successfully before.
  Reply With Quote
Old 6th December 2005, 03:21 PM   #33
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
Quote:
Originally posted by mpm32
Why not use a router? I've used a router on aluminum successfully before.
Second that. Spiral bit works well.

Sheldon
  Reply With Quote
Old 6th December 2005, 03:41 PM   #34
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Quote:
Why not use a router? I've used a router on aluminum successfully before.
Quote:
Second that. Spiral bit works well.
Stellar idea Gents!! I hope I can find a bit with a 1 1/2" long flute (the thickness of the plinth), otherwise I guess I'll have to cut from both sides.

Looks like I'm heading for the hardware store today.

Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 8th December 2005, 03:29 AM   #35
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
A bit of a setback that led to an improvement.

I was sitting in the shop contemplating my next move. Looking at the plinth, thinking about how I would veneer it, I noticed a small black line between the top Corian and the lead towards the back. I got off of my stool to take a closer look…my stomach dropped. The lamination had partially separated. I immediately inspected the rest of the pieces, and found no problems. In fact, the only part of the plinth that did separate, was on the top Corian surrounding what I had thought was a hairline crack of no consequence. Clearly this crack was in fact a full blown fracture in the top piece. The combination of the sanding vibration and the cold/warm cycling of the shop temp. had caused it to separate on both sides of the crack, fortunately I caught it before it fully de-laminated.

After several minutes of colorful superlatives, I considered my options and decided to go ahead with an approach I had considered originally, but thought would be to labor intensive….

Click the image to open in full size.

… what you see here is 56 1” 8-32 socket head cap screws stitching the whole thing together. You can see the crack on the lower right. The blemish on the left is the results of having a drill bit break. I was able (eventually) to remove the bit, but the punch I used to push the bit through a hole I drilled on the bottom mushroomed. When I drove the punch out with yet another punch, it blew a chunk of the Corian out with it. I epoxied the piece back on, and after it cured re-drilled. This job wasn’t as bad as I first thought it would be with one notable exception…DRILLING!! I thought the biggest job would be the tapping. Corian, lead, epoxy, and lead are all notorious for loading up a drill bit, put the four together and you have a major PITA! I found myself cleaning out the drill flutes with a carbide scribe 2-3 times per hole.

I feel the whole thing was worth it though. Not only is the Corian sucked up tight again, but the rigidity of the whole thing is at least an order of magnitude better, yet its still very acoustically dead. I haven’t decided if I will do the bottom plinth yet, but I will probably talk myself into it.

Now, where was I?…..
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 12th December 2005, 04:59 AM   #36
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
I started the weekend by filling in the screw heads from the cap screws in the top plinth, and roughed in the bottom plinth with a router and a carbide bit (thanx again for the idea mpm32 ), the rest of my time was spent on the motor….

Click the image to open in full size.

…like a lot of people, I’ve been debating between DC (quite operation and easy supply), and AC (speed locks on frequency). After going back and forth, I decided if I could make a quite AC motor assembly, the potential speed accuracy would be worth the effort. I intend on building a frequency switchable Wien Bridge power source for it.

I started out by making a mounting plate out of ¼” steel. I mounted it to a piece of ABS pipe by running a bead of silicon glue around the inside edge, and placing it over the mounting plate. The mounting plate is slightly undersized, leaving a small gap for the silicon to fill. The plate is essentially suspended by a thin rubber ring…

Click the image to open in full size.

… I then mounted my motor, a 3W 300 rpm Hurst from an old Harmon Kardon table. I had completely sealed the unit in silicon glue earlier…

Click the image to open in full size.

Click the image to open in full size.

…Why seal up the motor ? So it would survive me doing this…

Click the image to open in full size.

…I filled up the case with iron powder left over from my transformer experiments . After vibrating , and tamping it down, I sealed it up with an aluminum disc epoxied in place. In addition to the obvious sound dampening, it also acts as a mondo magnetic and electric field shield, as well as a ballast. I would guess the weight at around 10 lbs.

How quite is it?…BWHAA-HA-HA_HA…sitting on a piece of 1/32” thick dense cell foam I plan on using for an anti-skid surface on the bottom, you have to put your ear ON it to hear the hum. Even then, the miniscule noise of a 1/8” shaft turning in a lubed bronze bushing is equally loud

Next I’ll be working on my pulley, I really have a need to see it spinning under its own power .

Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 12th December 2005, 06:29 PM   #37
diyAudio Member
 
Join Date: Feb 2004
Location: Lincolnshire, UK
Lookin' good!!

Does the Hurst have any sort of thrust bearing on the bottom of the shaft?
  Reply With Quote
Old 12th December 2005, 07:00 PM   #38
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Quote:
Lookin' good!!
Thank you.

Quote:
Does the Hurst have any sort of thrust bearing on the bottom of the shaft?
It has a thust bearing, but not at the bottom. A brass washer is pressed about a 5/8" down from the top, this rides on a washer of some stiff synthetic material ,that in turn, rides on the brass bushing in the motor. The "cup" magnet is pressed on from the bottom with the same style washer, sandwiching the bushing between it and the top washer(s). Basically, the magnet "hangs" from the top washer.

Hurst still makes the motor, you can see it here..its the first one on the list...


http://www.myhurst.com/hurstmfg/qser...chronous+Motor

Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 12th December 2005, 08:17 PM   #39
mpm32 is offline mpm32  United States
diyAudio Member
 
Join Date: Dec 2003
Location: New England
Hey no problem. Glad I could make a suggestion that could help you build something I would love to be able to. Plus, I didn't want to have to wait for you to do all of that milling to see new pictures.
  Reply With Quote
Old 19th December 2005, 04:16 PM   #40
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Another weekend in the shop…this time however, it was a 2 step forward - 3 steps back situation.

Quote:
How quite is it?…BWHAA-HA-HA_HA…sitting on a piece of 1/32” thick dense cell foam I plan on using for an anti-skid surface on the bottom, you have to put your ear ON it to hear the hum. Even then, the miniscule noise of a 1/8” shaft turning in a lubed bronze bushing is equally loud
Well yes..with no load. And then this only applies to the stationary bits, not the armature. Playing around with the spinning motor, I noticed that when I put a load on the motor by pinching the spinning shaft, the overall noise increased slightly, but more importantly, the shaft vibrated a bunch. Left unchecked, I felt that this would buzz the heck out of the Mylar tape belt. I set out to make a harmonic balancer/flywheel pulley assembly. I constructed a copper/lead laminate wheel and built the pulley assembly you see here sitting next to the motor….

Click the image to open in full size.

… It did virtually eliminate the shaft vibration, it also however loaded the motor considerably. The weight (around 8 oz.) was to much of a vertical load for the motor, pushing on the brass washer that the armature hangs from. It increased the motor noise to a point of being able to here it a couple feet away…this will not do. I then made a conventional pulley to see how big a problem the vibrating shaft was. It’s big. Running the table with the pulley shown on the motor, sets up a vibration on the belt strong enough that you can actually see it…this also will not do.

So, a heavy pulley assembly acts as a harmonic balancer, killing shaft vibration, but increases motor noise. A light pulley doesn’t raise the noise of the motor significantly, but leaves the shaft vibration unchecked, which in turn, vibrates the heck out of the belt.

My next attempt will be a hydraulic dampener of some sort. The ideal fluid ( to my mind anyway) would be mercury, but being hazardous would require extra care to make sure its sealed. Second choice would be a heavy oil. I will probably try oil first.

Another thing that became painfully obvious playing with the belt drive, is how freakin’ critical alignment is. I found that tilting the motor a couple thousandths of an inch with shims would cause the belt to “walk” up or down the pulley/belt groove. I believe the larger diameter of my low rpm pulley exasperates this problem relative to a high rpm setup running the belt directly on the motor shaft. So, I will be modifying my motor mount, and plinth, to accommodate a fine level adjustment.

This weekend will go into the “learning curve” category.

If anybody has some pulley noise dampener ideas, I’m all ears.

Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Corian for tube amp? Sherman Tubes / Valves 2 29th September 2004 11:55 PM
WTB Corian CV Swap Meet 4 27th September 2003 02:15 PM


New To Site? Need Help?

All times are GMT. The time now is 12:28 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2