Author Topic: new grommets from RetroLinear  (Read 5734 times)

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
new grommets from RetroLinear
« on: August 04, 2016, 02:40:33 AM »
Hello guys,

Yesterday I replaced the grommets and screws on a dozen of tonebars with the ones from RetroLinear. They have a perfect fit and were very easy to install. I used the method described by timengr1 in http://www.ep-forum.com/smf/index.php?topic=8280.0

The basic tone and sustain are good but it seems I have less bark than I had before on these keys. I was wondering if there are more people with the same experience? Should I install them on a different way or go for a set from Vintage Vibe?

Thanks Roy
« Last Edit: August 04, 2016, 06:57:08 AM by rhodesjuzz »
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline Tim Hodges

  • Vendor
  • Mark II
  • *****
  • Posts: 808
  • Tim
    • View Profile
    • Facebook
Re: new grommets from RetroLinear
« Reply #1 on: August 04, 2016, 06:12:00 AM »
Hi Roy,

It could be that those keys now need to be re-voiced. To me the bark sound will come from the voicing of the tine in relation to the pickup in a few ways.

The level of the tine next to the pickup (the preferred method is the end of the tine being slightly higher than the tip of the pickup) this give you harmonic with some fundamental. In conjunction with that the distance between the pickup and the tine should also help.

I don't think you'll need to buy another set of grommets to fix it.  :D
Bristol Electric Piano
UK

Facebook
YouTube
Reverb.com

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: new grommets from RetroLinear
« Reply #2 on: August 04, 2016, 06:32:38 AM »
Hi Roy,

It could be that those keys now need to be re-voiced. To me the bark sound will come from the voicing of the tine in relation to the pickup in a few ways.

The level of the tine next to the pickup (the preferred method is the end of the tine being slightly higher than the tip of the pickup) this give you harmonic with some fundamental. In conjunction with that the distance between the pickup and the tine should also help.

I don't think you'll need to buy another set of grommets to fix it.  :D

Thanks Tim,
I spent quite some time voicing these notes. Normally it takes just one ore a few minutes to voice a note (eg after replacing a tine or normal maintenance), but with the new grommets I find it hard to get the right amount of bark. Should the tonebars be higher or lower as a whole (if that is the right english way to put it? :) ) because of the different hardness in grommets?

 :D Roy

« Last Edit: August 04, 2016, 07:51:42 AM by rhodesjuzz »
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline Ben Bove

  • Vendor
  • MIDI Mark V
  • *****
  • Posts: 3279
  • Formerly bjammerz
    • View Profile
    • Retro Rentals Website
Re: new grommets from RetroLinear
« Reply #3 on: August 04, 2016, 05:39:19 PM »
Move pickups closer  ;D
Retro Rentals
Vintage Music Gear

http://www.RetroRentals.net
(818) 806-9606
info@retrorentals.net

FB: https://www.facebook.com/retrorentals.net/
IG: @RetroRentalsNet

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: new grommets from RetroLinear
« Reply #4 on: August 05, 2016, 02:39:42 AM »
Move pickups closer  ;D

Thanks for the tip, Ben! Unfortunately I already did that  :-\
For me moving the pickups is a standard procedure when it comes to voicing. Don't know if this is actually true, I'm just a rookie when it comes to maintaining a Rhodes compared to most of the people out here :-X

The bark is there, but I really have to strike the involved keys harder than before/than the others with the original grommets. It looks like the tonebars have less flexibility and maybe that will dampen the tone and/or don't allow the tonebar/tine to oscilate freely (man, I hope someone understand this crappy english  ;D)

I think I'll just reinstall the originals and try to obtain some other grommets, but that is a waste of money...

--Roy
« Last Edit: August 05, 2016, 02:41:41 AM by rhodesjuzz »
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline Ben Bove

  • Vendor
  • MIDI Mark V
  • *****
  • Posts: 3279
  • Formerly bjammerz
    • View Profile
    • Retro Rentals Website
Re: new grommets from RetroLinear
« Reply #5 on: August 05, 2016, 12:09:12 PM »
Before you do the whole job, maybe record audio on a couple notes?  Put some old grommets back on say 5 notes or so, and record new vs. old and post here?

Usually, grommets shouldn't affect the bark of a note so I'm curious.  Potentially new tonebar screws can change the position of the tonebar on a small scale (if you had bent ones before).
« Last Edit: August 05, 2016, 12:42:32 PM by Ben Bove »
Retro Rentals
Vintage Music Gear

http://www.RetroRentals.net
(818) 806-9606
info@retrorentals.net

FB: https://www.facebook.com/retrorentals.net/
IG: @RetroRentalsNet

Offline Tim Hodges

  • Vendor
  • Mark II
  • *****
  • Posts: 808
  • Tim
    • View Profile
    • Facebook
Re: new grommets from RetroLinear
« Reply #6 on: August 05, 2016, 01:51:24 PM »
Usually, grommets shouldn't affect the bark of a note so I'm curious.  Potentially new tonebar screws can change the position of the tonebar on a small scale (if you had bent ones before).

That's what I was thinking, are the screws tight on the grommets?
Bristol Electric Piano
UK

Facebook
YouTube
Reverb.com

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: new grommets from RetroLinear
« Reply #7 on: August 05, 2016, 02:10:54 PM »
Yes, they have a perfect fit but not too tight. After raising the tonebar it really improved the bark, but all of the other tonebars sit lower  :o

Except for the looks the set seems to be very good quality and fit perfect. I bought it quite a while ago but never had the time.

I doubt whether I should continue (i only replaced these on 10 tonebars) or buy the competitors set?

--Roy
« Last Edit: August 05, 2016, 02:12:55 PM by rhodesjuzz »
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline Ben Bove

  • Vendor
  • MIDI Mark V
  • *****
  • Posts: 3279
  • Formerly bjammerz
    • View Profile
    • Retro Rentals Website
Re: new grommets from RetroLinear
« Reply #8 on: August 05, 2016, 02:30:34 PM »
I would not worry about how the tonebars look as far as height goes, compared to others.  Tonebars can be all over the place in heights, as long as you have the right tone. 

I think if you ordered a different set of grommets, you may have the same issue.  I believe it to be something else
Retro Rentals
Vintage Music Gear

http://www.RetroRentals.net
(818) 806-9606
info@retrorentals.net

FB: https://www.facebook.com/retrorentals.net/
IG: @RetroRentalsNet

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: new grommets from RetroLinear
« Reply #9 on: August 05, 2016, 04:35:11 PM »
I would not worry about how the tonebars look as far as height goes, compared to others.  Tonebars can be all over the place in heights, as long as you have the right tone. 

I think if you ordered a different set of grommets, you may have the same issue.  I believe it to be something else

Thanks Ben! I think I'll just give it a go (that will only cost me time :) )
Are you by chance familiar with both VV and Retrolinear grommets?

Thanks! Roy
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline retro-mike

  • Vendor
  • Fiesta Red
  • *****
  • Posts: 47
    • View Profile
    • Retrolinear.com
Re: new grommets from RetroLinear
« Reply #10 on: August 05, 2016, 06:15:18 PM »
The grommets function is to isolate each note from one another and eliminate unwanted sympathetic vibrations.   For the grommet to function properly it requires a semi-snug fit,  it must have the proper hardness and be made from the correct materials so it doesn't dry out, crack and split.
The kits come complete with screws and washers because over the last 30-40 years most of these pianos have had "improvised" repairs and its optimal to have straight / uniform screws for a good setup. If the tone bar mounting screws are bent it will cause the tone bar assembly to shimmy left and right.  Having the tone bars pivoting left/right is quite a nuisance in setup and it moves the head of the Tine away from the pickup which is not optimal.  Ideally you want the end of the tine centered on the pickup.

Our screws and washers have a plating which resists rust/corrosion, this plating was chosen for its function.  We have had some folks say "hey they aren't chrome plated" but keep in mind -it's not a cosmetic part and the goal is to produce a long lasting reliable part that doesn't break down, rust etc.

"Bark" comes from setup and voicing.  The grommet has no effect on the percussive side of the piano or the dynamic response of attack.

Roy, as we discussed in email your Rhodes has a mixture of tines which creates strike-line issues! Setting up your Rhodes is a complex task to achieve without addressing the mixed tines issue. When you have all 3 types of tines in a Rhodes the strike line is not consistent and getting consistent sounds is tough. Please keep that in mind.
When installing new grommets, screws, washers you will have to reset escapement on the entire harp.  Escapement is set by the 1st screw on the tone bar, closest to the keys. you need to take the square part of the tine (tine block) and place that on the harp as follows. See escapement_1.jpg
Picture #2 shows the height difference.

Start at one end of the harp and set escapement for each note. Set escapement at  .375" or 9.5mm.
That is the correct procedure. This will give you a good baseline to start voicing which is where the bark and dynamics comes into play.

Please accept our apologies on your difficulties,  I cannot express enough to our clients and customers that the sum of a good Rhodes isn't just about bolting new parts in and getting instant results! We have had dozens of folks buy $400-600 in parts off the internet, install them into their pianos and have had poor results at best - a good deal of these pianos come to our shop essentially destroyed..

Good parts can solve functional problems etc, but good setups make good instruments that's what really counts with a Rhodes.

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: new grommets from RetroLinear
« Reply #11 on: August 06, 2016, 03:52:03 PM »
Hello Mike,

Thank you very much for your reply. I hope my questions didn't come off as a complaint. That was not my intention at all, but merely as my interest about how other people apply these grommets in various types of Rhodes pianos.

Of course, apologies are certainly not needed and if they are, they should come from my side :)

As for the mixed tines, I eliminated the Schallers, so I'm left with torringtons in the bass and mid section. The singers reside at the treble side of the harp.

Your tips really helped a lot. I noticed the tine block doesn't fit underneath any of the tonebars. At the torrington side I measure about 7mm and 9mm at the singer tonebars. I increased the torrington escapement up to 8mm where the new grommets/screws are installed. The sound is ok!

If I increase the escapement anywhere to 9,5 mm I have more dynamics and a reasonable amount of bark, but not the sound I like. That is one of the reasons I'm quite aware of the fact that maintaining a Rhodes is not only a matter of bolting in new parts ;)

The reason why I want to replace the grommets and screws is that I have several bent screws and notes without proper sustain where the grommets are extremely pancaked.

Thanks again for your answer and pictures. I will continue the job allthough I can't get used to the method Tim adviced ;)

--Roy
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline David Aubke

  • Vendor
  • Mark V
  • *****
  • Posts: 1196
    • View Profile
    • Shadetree Keys
Re: new grommets from RetroLinear
« Reply #12 on: August 08, 2016, 07:34:37 AM »
We have had some folks say "hey they aren't chrome plated" but keep in mind -it's not a cosmetic part and the goal is to produce a long lasting reliable part that doesn't break down, rust etc.

Believe I'm one of those folks. But for the record I would have said "hey, they aren't nickel plated".
« Last Edit: August 08, 2016, 07:41:00 AM by David Aubke »
Dave Aubke
Shadetree Keys

Offline Tim Hodges

  • Vendor
  • Mark II
  • *****
  • Posts: 808
  • Tim
    • View Profile
    • Facebook
Re: new grommets from RetroLinear
« Reply #13 on: August 08, 2016, 07:58:35 AM »
I will continue the job allthough I can't get used to the method Tim adviced ;)
--Roy

That's because I'm magic.  ;D
Bristol Electric Piano
UK

Facebook
YouTube
Reverb.com

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: new grommets from RetroLinear
« Reply #14 on: August 08, 2016, 08:22:10 AM »
I will continue the job allthough I can't get used to the method Tim adviced ;)
--Roy

That's because I'm magic.  ;D

Haha,.....Sorry about the confusion, but I meant another Tim: Tim Warneck from Retrolinear in an other topic (see beginning of this topic http://ep-forum.com/smf/index.php?topic=8280.msg43795#msg43795 )

--Roy
« Last Edit: August 08, 2016, 01:32:18 PM by rhodesjuzz »
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline Chris Carroll

  • Vendor
  • Mark I
  • *****
  • Posts: 139
    • View Profile
    • http://www.vintagevibe.com
Vintage Vibe Grommet / Screw info
« Reply #15 on: August 10, 2016, 03:17:06 PM »
https://youtu.be/HRabYzSZ4cc

This video I hope will shed some light on misinformation out there about grommets/ screws and their application. There are some people that push grommets without the proper screw. Here is some insight on that.
« Last Edit: August 10, 2016, 03:19:21 PM by Chris Carroll »
Vintage Vibe will do all we can to help anyone out in a fair and honest way. Call us up or email anytime.  "Love is the answer"

Offline David Aubke

  • Vendor
  • Mark V
  • *****
  • Posts: 1196
    • View Profile
    • Shadetree Keys
Re: Vintage Vibe Grommet / Screw info
« Reply #16 on: August 10, 2016, 05:13:00 PM »
https://youtu.be/HRabYzSZ4cc

This video I hope will shed some light on misinformation out there about grommets/ screws and their application. There are some people that push grommets without the proper screw. Here is some insight on that.

I'm a little confused about all of the effort spent debunking the one-grommet-fits-all myth. I don't recall ever having seen that claim.
Dave Aubke
Shadetree Keys

Offline rhodesjuzz

  • Mark I
  • ****
  • Posts: 230
    • View Profile
Re: Vintage Vibe Grommet / Screw info
« Reply #17 on: August 10, 2016, 06:27:06 PM »
Thanks Chris, this vid is very helpful. I already noticed the screws in my '76 are slightly thicker than some different screws I collected through the years (i know 2 of them come from a '78 Rhodes)

I now have a few ep-service grommets installed with the original screws which seem to work fine but quite a few screws are bent so I really have to install a complete set.

--Roy
« Last Edit: August 10, 2016, 06:29:58 PM by rhodesjuzz »
1976 Rhodes Suitcase 73 <effects loop || EHX Holy Grail Nano>
Line 6 midi keys
Scarbee Mark I, A-200 and Classic EP-88S

Offline pnoboy

  • Mark I
  • ****
  • Posts: 393
    • View Profile
Re: new grommets from RetroLinear
« Reply #18 on: August 11, 2016, 03:00:17 PM »
The grommets function is to isolate each note from one another and eliminate unwanted sympathetic vibrations.   For the grommet to function properly it requires a semi-snug fit,  it must have the proper hardness and be made from the correct materials so it doesn't dry out, crack and split.
The kits come complete with screws and washers because over the last 30-40 years most of these pianos have had "improvised" repairs and its optimal to have straight / uniform screws for a good setup. If the tone bar mounting screws are bent it will cause the tone bar assembly to shimmy left and right.  Having the tone bars pivoting left/right is quite a nuisance in setup and it moves the head of the Tine away from the pickup which is not optimal.  Ideally you want the end of the tine centered on the pickup.

Our screws and washers have a plating which resists rust/corrosion, this plating was chosen for its function.  We have had some folks say "hey they aren't chrome plated" but keep in mind -it's not a cosmetic part and the goal is to produce a long lasting reliable part that doesn't break down, rust etc.

"Bark" comes from setup and voicing.  The grommet has no effect on the percussive side of the piano or the dynamic response of attack.

Roy, as we discussed in email your Rhodes has a mixture of tines which creates strike-line issues! Setting up your Rhodes is a complex task to achieve without addressing the mixed tines issue. When you have all 3 types of tines in a Rhodes the strike line is not consistent and getting consistent sounds is tough. Please keep that in mind.
When installing new grommets, screws, washers you will have to reset escapement on the entire harp.  Escapement is set by the 1st screw on the tone bar, closest to the keys. you need to take the square part of the tine (tine block) and place that on the harp as follows. See escapement_1.jpg
Picture #2 shows the height difference.

Start at one end of the harp and set escapement for each note. Set escapement at  .375" or 9.5mm.
That is the correct procedure. This will give you a good baseline to start voicing which is where the bark and dynamics comes into play.

Please accept our apologies on your difficulties,  I cannot express enough to our clients and customers that the sum of a good Rhodes isn't just about bolting new parts in and getting instant results! We have had dozens of folks buy $400-600 in parts off the internet, install them into their pianos and have had poor results at best - a good deal of these pianos come to our shop essentially destroyed..

Good parts can solve functional problems etc, but good setups make good instruments that's what really counts with a Rhodes.

The Vintage Vibe video showed their screws and grommets.  The screws had quite a large diameter shank, which would necessitate that the wall thickness of their grommets be relatively thin.  I would be interested if you could post a comparison with your screws and grommets and explain in what ways your products may be different.

Offline retro-mike

  • Vendor
  • Fiesta Red
  • *****
  • Posts: 47
    • View Profile
    • Retrolinear.com
Re: new grommets from RetroLinear
« Reply #19 on: August 11, 2016, 06:59:01 PM »
If I can just make a blanket statement as this thread seems to have quite a few individuals heated.

There are many grommets available on the market, some right, some wrong, some are merely McMaster grommets being resold on ebay which are fine for use elsewhere but not as a Rhodes part.

RetroLinear has spent a considerable amount of time/funds on prototype batches of grommets and screws to get our recipe right.  As always I back my statements up with how our pianos sound when finished.   I'll provide honest sound advice but our customers make all final decisions on their purchases.

And to be blunt--   none of us parts manufactures are producing 6 types of screws for every era of Rhodes piano, that would be pointless. The only reason why there were so many screws used throughout the years was because the vendors changed.

Our grommets are identical to the originals. Back in 1989 Tim found a Rhodes parts supplier (MDS, Chicago, IL) He purchased original unused Rhodes grommets and we've cloned those - every detail dimensionally and chemically. The screws we produce are custom sized to fit these grommets. We have installed our grommets into over 100 pianos without any problems.  We also have a group of technicians using our grommets without any problems.

Moving along- traditionally mixing different era parts in a Rhodes does not pan out, it's safe to say that's a pretty factual statement. The forum search feature on this website can infinitely reinforce that statement.   The term "uniform production" obviously wasn't important in the span of Rhodes manufacturing, otherwise there would not be so many inconsistencies.

I constantly preach this to clients on the phone.  You have to use the right stuff to get the right results. You also need to understand what you are doing. There are specialist shops for a reason. The skills required to set these up RIGHT are heavily based on experience. For instance Tim has been working on Rhodes Pianos for 25 years, before the internet, I trust he knows how to produce a grommet.

Offline pnoboy

  • Mark I
  • ****
  • Posts: 393
    • View Profile
Re: new grommets from RetroLinear
« Reply #20 on: August 12, 2016, 07:20:09 AM »
Retro-Mike--

Thanks for the additional information you supplied.  If I may ask another question, you indicate that you use clones of the grommets used by Fender, both in dimension and in the type of rubber.  However, we all know that the original Fender grommets pancaked.  Therefore, why would we not assume that yours would pancake also? I hope this does not seem to be a hostile question--I am just a Rhodes owner trying to figure out whose grommets to buy.  I could extend this question to Vintage Vibe--have you good reason to say that your grommets won't pancake?

Offline David Aubke

  • Vendor
  • Mark V
  • *****
  • Posts: 1196
    • View Profile
    • Shadetree Keys
Re: new grommets from RetroLinear
« Reply #21 on: August 12, 2016, 07:31:46 AM »
Retro-Mike--

Thanks for the additional information you supplied.  If I may ask another question, you indicate that you use clones of the grommets used by Fender, both in dimension and in the type of rubber.  However, we all know that the original Fender grommets pancaked.  Therefore, why would we not assume that yours would pancake also? I hope this does not seem to be a hostile question--I am just a Rhodes owner trying to figure out whose grommets to buy.  I could extend this question to Vintage Vibe--have you good reason to say that your grommets won't pancake?

I think it's unrealistic to expect any flexible grommet to hold its form over years of constant compression. I consider these to be one of the consumable components of a Rhodes.
Dave Aubke
Shadetree Keys

Offline pnoboy

  • Mark I
  • ****
  • Posts: 393
    • View Profile
Re: new grommets from RetroLinear
« Reply #22 on: August 12, 2016, 07:37:48 AM »
Retro-Mike--

Thanks for the additional information you supplied.  If I may ask another question, you indicate that you use clones of the grommets used by Fender, both in dimension and in the type of rubber.  However, we all know that the original Fender grommets pancaked.  Therefore, why would we not assume that yours would pancake also? I hope this does not seem to be a hostile question--I am just a Rhodes owner trying to figure out whose grommets to buy.  I could extend this question to Vintage Vibe--have you good reason to say that your grommets won't pancake?

I think it's unrealistic to expect any flexible grommet to hold its form over years of constant compression. I consider these to be one of the consumable components of a Rhodes.

David,

You may well be correct.  However, there could be a large variation in how long grommets made with different rubber compounds take to pancake.  If a given material pancaked in 1 year, you'd probably not be very happy, but if it took 10 years you might be very happy with it.  I don't have enough knowledge about rubber compounds to know what to expect from grommets, but it seems like a legit area of inquiry.
« Last Edit: August 12, 2016, 07:39:25 AM by pnoboy »

Offline pnoboy

  • Mark I
  • ****
  • Posts: 393
    • View Profile
Re: new grommets from RetroLinear
« Reply #23 on: August 12, 2016, 07:55:22 AM »
Google to the rescue.  Seehttps://www.professionalplastics.com/professionalplastics/RubberandElastomersOverview.pdf.  The chart on page 2 shows the relative compression-set resistance of quite a few types of rubber.  Hopefully, the companies selling grommets selected one of the materials whose compression set was rated a 1.  I found this same chart reproduced elsewhere, so hopefully its information is trustworthy.

Offline David Aubke

  • Vendor
  • Mark V
  • *****
  • Posts: 1196
    • View Profile
    • Shadetree Keys
Re: new grommets from RetroLinear
« Reply #24 on: August 12, 2016, 07:59:41 AM »
Hopefully, the companies selling grommets selected one of the materials whose compression set was rated a 1.

I think they should select a material with the best combination of qualities. I'm not sure it would be a good idea to put longevity at the top of the priority list.
Dave Aubke
Shadetree Keys

Offline Tim Hodges

  • Vendor
  • Mark II
  • *****
  • Posts: 808
  • Tim
    • View Profile
    • Facebook
Re: new grommets from RetroLinear
« Reply #25 on: August 12, 2016, 09:10:59 AM »
Hopefully, the companies selling grommets selected one of the materials whose compression set was rated a 1.

I think they should select a material with the best combination of qualities. I'm not sure it would be a good idea to put longevity at the top of the priority list.

Agreed, by making longevity paramount it may affect other aspects such as it's ability to isolate vibrations effectively (don't quote me on this). Either way with the amount of pressure these things are exerted to it's no surprise that after x many years they will distort. As you said Dave it's an expendable component. 
Bristol Electric Piano
UK

Facebook
YouTube
Reverb.com

Offline David Aubke

  • Vendor
  • Mark V
  • *****
  • Posts: 1196
    • View Profile
    • Shadetree Keys
Re: new grommets from RetroLinear
« Reply #26 on: August 12, 2016, 09:20:56 AM »
by making longevity paramount it may affect other aspects such as it's ability to isolate vibrations effectively

just had to...
Dave Aubke
Shadetree Keys

Offline Tim Hodges

  • Vendor
  • Mark II
  • *****
  • Posts: 808
  • Tim
    • View Profile
    • Facebook
Re: new grommets from RetroLinear
« Reply #27 on: August 12, 2016, 09:22:27 AM »
Ba dum tshhh  ::)
Bristol Electric Piano
UK

Facebook
YouTube
Reverb.com

Offline pnoboy

  • Mark I
  • ****
  • Posts: 393
    • View Profile
Re: new grommets from RetroLinear
« Reply #28 on: August 12, 2016, 01:10:38 PM »
Hopefully, the companies selling grommets selected one of the materials whose compression set was rated a 1.

I think they should select a material with the best combination of qualities. I'm not sure it would be a good idea to put longevity at the top of the priority list.

Agreed, by making longevity paramount it may affect other aspects such as it's ability to isolate vibrations effectively (don't quote me on this). Either way with the amount of pressure these things are exerted to it's no surprise that after x many years they will distort. As you said Dave it's an expendable component.

Again, let me mention my lack of expertise on the subject before I comment further, but I suspect that the only 3 parameters of the rubber that would be of principal importance are its longevity, its durometer, and its damping factor.  It should be no problem at all to select a rubber of the proper durometer from the fairly large numbers of rubber compounds whose compression-set rating was a one.  I don't think the damping coefficients would vary much--notice that almost all the rubbers in the PDF I previously referenced tested almost the same for "resilience," which is the characteristic most closely associated with damping factor.  In general, I don't think there's much magic in the grommets--pick an appropriate rubber compound, select the dimensions, pick a screw whose fit to the grommet is appropriate and you're pretty much done.

Offline Tim W

  • Sparkletop
  • ***
  • Posts: 80
    • View Profile
    • Retrolinear Inc.
Re: new grommets from RetroLinear
« Reply #29 on: August 12, 2016, 03:40:21 PM »
I guess we will need to rename this thread  Grommetgate.  :)

Hopefully you all will be pleased to know that yes, I stared at the same tables, consulted with people in the elastomer industry, and had testing done on original factory parts I bought in 1989.  We worked with our supplier and selected a compound with the right qualities and durometer, based off the original.  Even within a specific compound, there are several quality grades.  We selected a high quality grade compound, probably better than what Rhodes originally used, but I cannot say for sure for obvious reasons (I wouldn't even know who to ask, and they probably wouldn't remember anyway).  We may need to wait another 10-20 years to find out how the grommets hold up long term.  I can say that our grommets have been in production since about 2008, they are in my personal instrument that had pancaked original grommets, and as of 2016 they still look great and function as intended.  I doubt they will change appreciably in the next 5-10 years since they haven't changed yet.

If we didn't select the appropriate compound and durometer, it is unlikely voicing would even stay consistent on a given piano as the grommets would deform in a very short period.  This is why we had grommets made in the first place (during the Keyboard Cottage years) because *every* Rhodes supplier at the time was selling McMaster or McMaster style grommets. They were often sold with flat head screws and captive finishing washers in most cases (as was in the Mk V).  They NEVER fit properly and 2 hours after voicing the piano everything would be all over the place again.  Playing the piano would also cause voicing to drift!  I did not want pianos in the field doing this, so we decided to have grommets produced ourselves.  It wasn't long after we released ours that original looking grommets became available from other sources.

Yes our grommets are more expensive.  They are sourced here in the US, and made from high quality material.  The fit and finish is superior.  There are no deformities, flash, wrinkles, bubbles, etc.  All our grommets are consistent, and we provide a few extras just in case.

Our screws are custom produced with the correct shoulder to fit in the grommet properly.  Again, here in the US.  We opted not to have them nickel plated to keep the price lower, as it is not an externally visible part.  They are still plated, however, for rust and corrosion protection.  Quality thick flat washers, finished the same as our screws, were also chosen.

At RetroLinear we do our best to do things the right way and put the effort where it really counts.  This is why discerning clients keep returning to us.  Our instruments feel great, sound great, and our parts and electronics are very reliable.  And the end results are obvious, if you take the time to listen and compare.

Tim
retrolinear.com
« Last Edit: August 12, 2016, 03:46:39 PM by timengr1 »