Harp Shims

[Chris_2112]

Good Morning!  
I'm trying to make my '75 Mk1 Stage piano more playable, right now the action is heavy and cumbersome especially on the lower end.  I see the shims sitting on top of the aluminum harp supports and I've read here that experimenting with lowering these might help me out.  To those who have replaced the shims, what did you use for a replacement?  Does the exisiting shim just pop right off or is it glued down?  I apologize if this is a dumb question and thanks in advance for any suggestions you have.

-Chris

[dnarkosis]

This topic would interest me as well, since cutting these things requires equipment capable of making very fine cuts. I have never had worked on a Rhodes that did not have them glued down -- which is a bit of a hassle, especially if you would like to play the keyboard for a couple of months after resetting the shims to see if it is what you want.

Someone once suggested just using different thickness washers beneath the screws, but that apparently can bow the harp itself (I've never tried it). It seems there should be a more convenient alternative.

In any event, John Della Vecchia posted this to the Yahoo Rhodes Tech group back in 2003:

*Setting up the harp, and the importance of shims*

The harp is the "heart" of the rhodes, and ultimately the component that produces the sound – the defining factor of the piano. Most new techs approach harp setup in terms of how it relates to the rest of the action, but in reality in can be completely built detached from the piano. There are documented specs for each component of the harp, both measured and visual, so having the harp sitting on your workbench does not inhibit you in any significant way. EXCEPT as it relates to escapement, which can be solved by harp support shims.

I have found that setting to the harp to specific specs, THEN adjusting for escapement by raising and lowering is the most consistent way of getting desired results. Most times, it may be that you only need to reduce the bass shim by an 1/8in. But you have the greatest control over your escapement on a global level with shims. Once you have the harp set, and then have your action set – put the two together, adjust for escapement and strike line. You can then adjust dampers for your settings.

Notes for setting up the harp:

1. I ALWAYS make sure that the pickups aligned. This is usually not a big ordeal, as only 2-3 will be higher or lower than the rest. But how can you set consistent strike line if your tines are at different height angles to match timbre?

2. If, for instance, you go down the length of the harp and set the tonebars to 3/8in (factory, and the only spec I use for this operation), and then go along the back and set timbre – your setting of 3/8 will ALWAYS turn out higher, incrementally. Some might say "who cares?", but CONSISTENCY is paramount to setting up a harp, whether it is separate or mounted. So I always make my first adjustment 1/16in lower to compensate for timbre travel. And this is obviously assuming that you are starting out with tonebars that are basically set, not with tines pointing way up into the wall. I then make another pass to adjust any inconsistencies.

3. Timbre is a players personal choice. I always ask the player what his/her preference in sound is. If they have no idea, I ask them what rhodes recordings they love. But as a general rule, I set just above dead center of the pickup – EXCEPT in the bass register, where it is a bit higher. This gives the bass a more rounder sound but is not a jarring transition. You may experiment with setting the upper flat tonebars a bit higher also.

Notes on shims:

1. After you have a clean harp, put it on the supports. Play some notes in all registers. Do you, as an example, notice that when you play below middle C or so that you feel the hammer bounce back in the cam – causing a little "bump" in your action? This means your escapement is too high in the lower register. Take off the bass shim and replace it with an 1/8in shim and see what results you get – which is a reduction of 1/8in from the factory. This is an example of how to use shims to your advantage. Take this technique and apply it to any inconsistencies, I guarantee you can find a solution quickly and efficiently.

2. What type of material to use as shims? If you have, or a friend has, a good pro cabinet table saw, then you can accurately cut your own shims – even down to 1/32in. These saws have the necessary power and accuracy. I use any hardwood so the harp will not compress the shim. I would not suggest using soft pine. The only caveat is that if you cut your own shims, make sure you know how to "square" the wood. High quality table saws have fences that are very accurate, but if your wood is not square on one side, it is definitely not going to be evenly thick. You need a piece of wood that is evenly thick to get good escapement and strike line. I keep a stock of 1/32 and 1/8. If you cannot make your own shims, you can find a man-made material at your local home depot-type establishment.

There are obviously other variables which will affect this and any other procedure. But once you know the basic operations you can make informed decisions about other aspects of the piano.

[Chris_2112]

That's a very helpful post, thanks dnarkosis.  Next time I'm at Lowe's or HD I'll have to take a look and see what pre-made shims they have as I don't have many precise woodworking tools.  I remember seeing shims there but they were tapered, I'll have to look to see if they have any that are even.  If I lower the bass side by 1/8th" do I then need to lower the treble shim by that amount to maintain any kind of relativity?  I'd be inclined to say no as I believe the treble shim is only 1/8th", thus taking off 1/8th would mean no shim on the treble side at all.

Thanks

[Rob A]

I have a fully equipped shop. I would consider making custom shims for forum members as a courtesy. Let me know if there's interest.

Generally, I'd set up the machines to do a production run in a couple sizes, then hand those out to people wanting them until my stock ran out. I have a reasonable supply of hard maple around that would be well-suited for shimming.

From the information above, it seems that 1/32 and 1/8 would be a good start, and I reckon you could combine them to get increments of 1/32. I don't suppose you'd really know in advance what thickness would be ideal, so combining thin shims to get a working height seems like a smart way to go. So one 1/8 shim plus three 1/32 shims would give you the flexibility to get all kinds of heights. Thinking through a bit farther, a shim kit with one each 1/8, 1/16 and 1/32 would do it too.

[Ben Bove]

I've searched HD before and yes, they only have tapered (angled) shims, used for house framing I believe.

[Rob A]

Shims like that are used in hanging a door squarely in the roughed-in opening.

[dnarkosis]

Chris,
re: raising or lowering the treble: one doesn't necessarily have to have the harp absolutely level, though getting too far off will likely have some noticeable effect -- since your are altering the strikeline incrementally across the keyboard from one end to the other.

Rob, I'd be interested in giving your shims (a "proto-set," if you will) a try: my Stage 54 is currently sitting unplayed because of (1) a poorly soldered preamp (which I need to get fixed) and no shims -- I removed the shims to start from scratch, since the escapement was so far off (far too deep across the entire keyboard) I began to wonder if it had been altered in some odd way. I have avoided getting around to fixing it precisely because I looked for shims and could not really find anything suitable.

However you'd like to work it is fine with me: I'll pay for the materials and shipping, of course, and certainly for your trouble if that will help. But I think your idea is excellent: an important part that is awkward to find.

You can contact me through PM.
Thanks for the generous offer.
doug

[Rob A]

Gotcha covered. It will be  little bit before I'm set up to produce them since my basement is getting remodeled right now. Maybe 2-3 weeks from now.

I would only charge for materials if you wanted them in padauk or purpleheart instead of maple.  :wink:

[dnarkosis]

Many thanks, and absolutely no hurry.  I need to get the preamp soldered first (i.e., soldered correctly).

I would only charge for materials if you wanted them in padauk or purpleheart instead of maple

What, no teak? :roll:

[tnelson]

If you're near a lumberyard or woodworking shop, just get some random pieces of wood veneers. Sheets should be available in many thicknesses, easy to cut with a utility knife. Stack as needed to add up to different thicknesses.  Much easier than cutting thin pieces to thickness on a saw.  You can glue them together when you find the total thickness you want.

[dnarkosis]

If you're near a lumberyard or woodworking shop

Thanks; good idea; unfortunatley, I don't really know anyone with such a shop. Yes, I'm sure they're around, but, um, the mm, "locals" can be a bit squirrely about such things.

[tnelson]

Another possible source of scraps of wood veneer is a cabinet shop that makes kitchen cabinets or other architectural woodwork.  They go through loads of hardwood veneer because much of what they make is of plywood faced with veneer selected by the customer.  I doubt that the scraps are valued enough to be saved, because they work with large areas.

[shmuelyosef]

You can also get 1/32"  and 1/16" polyethylene at TAP Plastics nationwide, and you can cut it with a straightedge and utility knife

[prtarrell]

Hobby shops sell small sheets of plywood in 1/thirtysecond, 1/sixteenth, etc.  Very useful.   For experimenting, until one gets the perfect harp hieght (Blow distance),  cardboard front rail punchings working nicely.

[GetWithTheTines]

Hi guys,

I just picked up some basswood and craft plywood from Ace Hardware. It's in thicknesses of 1/16", /8", and 1/4". 

a) Do you think that this type of wood is suitable for shims or is it too soft?
b) How thick do shims typically need to be? I'm guessing they usually need to be very thin, so I should look for some veneer somewhere that's 1/32"?

Thanks!

[Cormac Long]

The shim is primarily affecting escapement.

To get an idea on how high it needs to be, I would first set the escapement screws of the bass tonebars to 3/8". Use the tonebar block of another tine to make this job easier. This is just a good and common starting point. Vintage Vibe have some video instruction on this step.

Then check the service manual for the minimum and maximum escapement settings for the various tonebars. You'll need to measure the distance from a raised hammer tip to its associated tine. I lowered a ruler and eyed this one. But it quickly unveiled that things were just too high in places. Now I could have lowered the escapement all-through to compensate, but it was just easier to lower the shims.

What I did was to remove the shims altogether and then set about using coins as wedges to raise the harp until I got the escapement measurements I required. I've set things to the max value in all cases. I felt that if I require lower distances in places, that the tonebar escapement screws will handle this.

I've yet to think about new shims. I might even just make the coins a permanent solution by fixing them in place. Even if just left loose, they will be well secured when the harp is bolted down. Unless someone can clarify why, I can't imagine that using wood is going to improve sound etc.

[sean]

Basswood should be just fine.

The only reason that metal is not ideal for the shims is that moisture in the air, salts on the metal surfaces, and electrolysis all work together to fuse the metals together.  They can become "welded" together from the corrosion.  Sometimes the harp mounting screws become almost locked because of this.

As Cormac said, shims are great for making large adjustments to the escapement.  The main benefit from using shims (instead of globally looser tonebar screws) is that you can set the tonebar screws tight enough to properly and securely hold the tine in place and still get huge escapement.

After you install the shims (or make any large escapement changes), take a few minutes to re-set the strikeline.

sean

[GetWithTheTines]

Thanks, guys. That's helpful. I might try the idea of getting a veneer and cutting it with a utility knife for the 1/32" shims.

[prtarrell]

Go to any good model airplane hobby shop.  They sell plywood in  small sheets. 1/32, 1/16, etc.  buy the 1/32 and double up if necessary.  Plywood is very stable. As I recall,  the brand is Sig. Cut it with a hack saw blade.