machining press fit vs loctite

[jdedmon91]

Depending on the application. Like when I’m making something that I absolutely don’t want to move, like a speed handle that I’ve made. I want to press fits, but for things for that just need to stay together I use bearing mount locktite. It is easier to machine a slip fit then lock them together however like I said for something that won’t move press fit is the only way


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[Mitch Alsup]

My question is: Is it reasonable to machine a close tolerance on the parts and then assemble them with loctite? If so which variant would be best?

I recently did a similar job (for a telescope) where I used a 0.247 drill into 6061 which results in a thumb press fit of a 1/8-1/4 ball bearing retained only by tension around the bearing yet can be pushed out with a allen wrench from the other side. This is what we generally call "machined right the first time".

Alternately there are ways to put a slit near the bearing and use a screw to apply tension across (and around) to hold the bearing in place.

On the other hand: 6mm is pretty small for a shaft--for example the drive shaft in my C11 (circa 1989) is at least 3/8" solid steel with a bronze gear pressed on and hobbed on the shaft to fit the driven gear. Since stiffness increases quartically with diameter a 10mm shaft is (10/6)**4 = 7.7× stiffer.

 

[Tozguy]

The forces will be small and the rotations very low, less then one rpm on all parts.

My question is: Is it reasonable to machine a close tolerance on the parts and then assemble them with loctite? If so which variant would be best?

I would say that a Loctite product is an option in this case but there are many different ones for specific clearances and metals. Choose the one best suited to your needs then check formats and availability. You will get some valid recommendations from us but it is worth doing some research for yourself. The link that Karl provided is worth exploring.

 

[ch2co]

Just wondering what type of astrophotography camera mount assembly? A tracking mount? What kind of camera? Any and all details welcome. (Please)

And to just keep in line with the subject, I would go with the Loctite method.

 

[dansawyer]

Just wondering what type of astrophotography camera mount assembly? A tracking mount? What kind of camera? Any and all details welcome. (Please)

And to just keep in line with the subject, I would go with the Loctite method.

A reply to ch2co, sorry for the delay; I missed the question. Thank you for asking. The objective is Deep Sky Objects. The first attempts will be with a 90 mm F4 macro lens. The device will be an Arduino controlled stepping motor with 3 reduction gears There is a picture of the bearing box in the thread 'my first jig'. I will forward gear pictures in a couple of weeks

 

[dansawyer]

Thank everyone for the inputs. There is a second part to this project for the shaft to hold the camera. The shaft is about 12 inches long and .628 inch in diameter. The bearing id is .635. Based on the above recommendations I will machine the shaft to a slip fit and use bearing mount Loctite. This is still in progress.