Tinker cutter grinder?

[Sunset Machine]

(08-05-2012, 11:52 AM)NevadaBlue Wrote: Do you guys think I could use a bearing mounting compound to mount the bushings in the cutter head block? This seems to be a way to mount them without any critical machining. I could put the compound in the head, insert the bushings and then slip in the tool holder shaft and let it sit until the compound sets it seems.

I think Loctite 680 ("slip fit retainer") is the cat's meow. In steel, it's stronger than a press fit. The data sheet shows it isn't as strong in aluminum (75% of steel) and takes up to 72 hours for a full cure, starts to set in 30 minutes. Heat it to 250C (technical term: smokin' hot) and it melts. I think it would work great.

[dallen]

why do the bushing need to be loctited into the arms they aren't going to be having any real force applied to them and they are only going to be moved in fractions of a turn, the biggest thing that they will be for is to give a smooth free sliding fit for the pivot shaft, which a press fit should give plenty of support for, only draw back I see to using a press fit is that you will have to ream or bore the bushings after installation.

[stevec]

(08-06-2012, 10:09 AM)dallen Wrote: why do the bushing need to be loctited into the arms they aren't going to be having any real force applied to them and they are only going to be moved in fractions of a turn, the biggest thing that they will be for is to give a smooth free sliding fit for the pivot shaft, which a press fit should give plenty of support for, only draw back I see to using a press fit is that you will have to ream or bore the bushings after installation.

I go along with dallen, except the "only draw back I see to using a press fit is that you will have to ream or bore the bushings after installation."
A comfortable press fit wouldn't shrink the bore of the bushings enough to require reaming?

[DaveH]

DaveH

[Sunset Machine]

With a press fit, you have 2 precise dimensions to hold accurately and run the risk of ruining one and/or its alignment, and/or the casting. Of course it could be done that way, it's old school, but why do it that way here? $5 worth of gas to fetch a $10 bottle of loctite? I'd accept that, but...

"a way to mount them without any critical machining"

[DaveH]

I think even with loctite one will still have to accurately hold the 2 dimensions. There has to be some sort of accurate locating.

DaveH

[NevadaBlue]

I guess my thoughts were that the precise ground shaft would align the two bushings accurately enough when used with the loctite and that wouldn't require such an accurate boring job (I've never bored anything on the mill yet) or honing either. That was my hope anyway...

[Highpower]

(08-08-2012, 11:05 PM)NevadaBlue Wrote: I guess my thoughts were that the precise ground shaft would align the two bushings accurately enough when used with the loctite and that wouldn't require such an accurate boring job (I've never bored anything on the mill yet) or honing either. That was my hope anyway...

I would think that securing the bushings/bearings with Loc-tite (sleeve retainer) would be fine for aligning them with the shaft. The issue then would be aligning the shaft to be parallel/perpendicular to your grinding wheel/cup so that it tracks correctly across your abrasive. You may have to shim/adjust your base castings to do that.

As long as the shaft is pointing in the right direction when you are done, I don't see a problem with it myself. Mill heads are accurately bored and tightly fitted with precision bearings. Does that mean the spindle is always in tram with the table?

[stevec]

(08-08-2012, 11:05 PM)NevadaBlue Wrote: (I've never bored anything on the mill yet) or honing either. That was my hope anyway...

Ken, I'm probably going to get my knuckles rapped for this,but, maybe the Tinker cutter grinder is a little too "advanced" a project for you at this stage?

[NevadaBlue]

no knuckle rapping from me, you may be right! I'm not in a hurry for this to be done so I'm hoping to gain the skills I need before I actually tackle the difficult stuff. Thanks for the advice, I appreciate it.
I'll probably do the rough work that doesn't require the accuracy and then let the thing sit until I feel 'fit' to finish it.