Lyndon Smith - Posted - 04/13/2013:  08:16:57

How much clearance should be allowed between a tension hoop and the rim and a flesh hoop and a rim?

Bearing in mind that two layers of skin will go between the tension hoop and the rim but only one layer between the flesh hoop and the rim.

I am going to use a calf or goat skin head.

I am trying to work out the diameters of the rim hardware for my 11" and 8" test beds...

jbalch - Posted - 04/13/2013:  11:10:18

Maybe some of the builders around here will respond with their measurements.  But from the perspective of one who mounts lots of hide heads, I can say this:

1. the most important thing is that the flesh hoop is properly sized relative to the tension hoop. The flesh hoop should fit well underneath the tension hoop.  Ideally the outside diameter (o.d.) of the flesh hoop will be very slightly smaller that the o.d. of the tension hoop.  The inside diameters (i.d.) of the two rings should be about the same size.

2. you need sufficient space between the hoops and the rim/ tone ring to tuck two layers of hide - in the thickness you plan to mount. More space is fine.  The tension hoops need not be too tight to the rim. A little extra space is generally a good thing.

I observe a good bit of variation in how tight the tension hoop fits to the rim. Some vintage banjos fit so tightly that mounting a new hide is VERY difficult.  On the other hand, I think that some builders deliberately use oversized hoops to allow for mounting very thick hides.  That seemed to be so on a banjo I once owned by Johannes Bonefaas.  There was a big gap between the hoops and rim on that banjo (to accommodate a thick goat hide head - with the hair on). The Bonefaas tension hoop was so big that the flesh hoop had a tendency to pull up inside.

I prefer to mount hides that range between .013in. and .016in. thick. Much thicker than that and I have difficulty using my hardware.  I use an 11" rim with a Stew-Mac tension hoop.  It looks like the i.d. of the Stew Mac hoop is about 11 1/16". It is a tight squeeze with a hide about .016" thick. A little extra room would not hurt.

JB

Fathand - Posted - 04/13/2013:  11:18:22

I see tension hoops advertised as 3/16 thick and 11.5 outer so that would make 11 1/8 inner or 1/16" clearance which makes sense. I measured a prewar Waverly E2 grooved hoop at 1 1/16 -11 1/8 at different points. A late model notched hoop presumably from Sullivan at 11 - 11 1/16" and a cheap Chinese hoop at 11 1/4" inner diameter.  I would make a flesh hoop the same inner diameter as the tens hoop so that it sits square under it.

Lyndon Smith - Posted - 04/13/2013:  15:22:25

jbalch & Fathand: Thanks for your input. It sounds about right at 1/16" clearance...

Muddy Roads - Posted - 04/13/2013:  20:26:56

This might only apply to someone making their own tension hoops. BUT, when i build a tension hoop for a rim that's going to mount a Renaissance or other commercial synthetic head i make it so there's a 3/8" space at the widest (so if you push one side of the hoop up against the rim and measure the widest point.) vs. for a skin head, that gap is 1/8" or so. That usually leaves just enough room around all sides for the skin and so the flesh hoop doesn't suck up under the t-hoop.

just my method.

mbanza - Posted - 04/14/2013:  06:40:56

". . . to mount a Renaissance or other commercial synthetic head i make it so there's a 3/8" space at the widest. . ."

Is 3/8" the fraction you intended?

Lyndon Smith - Posted - 04/14/2013:  06:57:37

mbanza: I'd sort of settled on 1/8" space. That is, the inside diameter of the tension hoop is 1/8" larger than the outside diameter of the rim.

Are you saying that 1/8" is NOT enough?