takedown sleeve fit tolerances

[Richard B]

Interested in what tolerances people have achieved with the takedown sleeve system. I have just been through the process of fitting to my yew billets. Spent a lot of time trying to achieve a "perfect sliding fit", not convinced I did as well as I could have.
Basically did as follows:

1. fitted the brass sleeves to the shaped ends of the billets, being as careful as I could not to distort them.
2. Used a vice to shape the outer (stainless) sleeve to fit. One problem being that both the brass inner sleeves were now very slightly different in shape, so not possible to achieve a close fit with the stainless outer on both.
3. got round this by making a looser fit on one (mix of file on inner and vice on outer) and going for as accurate a fit as I could on the other.
4. Then glued the looser fitting sleeve into the outer sleeve, so no movement there.

The other sleeve (the one I went for as accurate) has a maximum gap of around 0.25mm at one point of the fit. This allows about 5mm of "wobble" at the end of the 36" limb (sorry about the mixed units!). Obviously there is no wobble on the other limb as it is glued into the outer sleeve.

The wobble is front to back so shouldn't affect string alignment. However, would have liked to have had less/no movement at all (however, would then have been impossible to push it into or take it out of the handle as the air wouldn't have been able to escape!).

How close a fit have others managed to achieve. What is possible using a vice to shape a piece of stainless steel piping and some emery paper/files to shape the brass inner?

As a point of comparison. A fine clearance hole on a 24mm bolt is defined as 25mm in diameter (i.e. a 1mm gap which would translate into 18mm wobble at the end of a 36" bow limb). An ISO "loose running fit" for a 25mm shaft in a machined bearing is defined as 0.26mm clearance (i.e. close to what I achieved).

[Weylin]

I had fits over this with my take downs. I used sand paper on the brass to do a lot of correction. Once you get close, slow down because you get to the final fit quicker than you expect at that point and you don't want it too loose. When you get close, try waxing the brass to see if that helps. It made a big difference on mine.

[Jim Davis]

Guess it's slightly to the side of the topic, but the above difficulties are why I like round-tube take-downs. I can put the limb/billet in my wood lathe and carefully work it down to a close fit. Then one end gets epoxied in and the other  gets an epoxy coat and is pushed into the other end of the tube, which has been waxed so the epoxy won't stick to the steel. Of course, the end of the previously glued limb has to be waxed too.

Or, with my screw together joint, both limbs are epoxied in.

Either way, no wobble.

Jim Davis

[Richard B]

asharrow,
certainly sounds easier with a machined fit.

[Aussie Yeoman]

Where're the screw-together fittings from and what draw weight can they handle?

[Jim Davis]

Where're the screw-together fittings from and what draw weight can they handle?

I made my own screw-together fittings. Not doable for everybody. I have only tested them up to about 50#. I think the wood would be the weakest part of the combination.

To me, the best thing about these  take-down methods is that they are a good way to use billets without having to splice them, but I do have a machining background. The plain tubing type though is doable for most of us.

Jim

[Eric Krewson]

I have only done one takedown fit, a real pain. the most important part of the fit to me was sleeve to sleeve which took some vice time to spread one and squeeze the other as well as a little draw filing of the metal.. My wood to sleeve fit was just OK but plenty of epoxy filled the gaps.

[Richard B]

A post on the 3 rivers review page for the takedown sleeve suggests:

"a neat trick for a super-fine fit was to spread a little quick-set epoxy such as JB Weld inside the female sleeve, put a thin layer of grease on male sleeve, then slide together when the epoxy set to putty-like consistency (don't let it get too hard-happens pretty quick). Pull the male sleeve right back out carefully, clean up the extra epoxy that was pushed around inside female sleeve, and let fully harden. Makes a perfect tight mating of surfaces that "pops" when you pull them apart!"

Has anyone tried this?

I am a bit annoyed by the play in my fit between the brass inner and the brass outer and was wondering whether this would be a good/durable way of correcting it?

Or should I just live with it , there is only a little play in the joint after all....