which loctite?

[tinkerer]

I've seen utube videos on machining. Sometimes they'll use a Loctite product to glue a piece on a mandrel to machine it. Then heat & remove it. But I can't remember what number they said & can't find the videos. Seems like it was 608?
Thanks Mike

[AOG]

It’s usualy 603 or 638 depending on the fit. Super glue can also be used if you take light cuts.

Tony

[Gas_mantle]

I usually go for 638 as long as the parts are a close fit. It cures quickly, even in as little as 5 mins it can withstand turning in the lathe. It's also easy to break apart with a bit of heat.

[Stuart]

Another vote for 638 great stuff

Stuart

[gerritv]

I use Weicon brand equivalent, half the price of Loctite and better dispenser:

[petertha]

I was just doing some of that tonight for the first time. I'll post some pics.

Part-1 6061 aluminum, about 1.4" dia x 0.2" thick, I used regular thick CA hobby glue. Maybe 1/16" dots about 3/8" apart on same alloy 2" diameter slug freshly finished in the lathe. During (traverse direction) machining I took off 0.010" each pass so there wouldn't be too much stress on the part. Worked great right to completion...until disassembly. It stuck too well. I torched it for 20 secs, then 40 secs, then 1 minute, no go. Finally it popped off with a chisel wedged into the joint. I was careful not to scratch the surface.

Part 2 same diameter but .6" hole in the middle so less glue contact area. I spread the dots wider maybe 1/2" apart. This time the part came off the mandrel on about the 5th pass. But I may have rushed the cure. Since I was in R&D mode I re-cleaned everything, sprayed the mandrel with kicker & same glue density on the part. As before I brought the 2 together with a dead center. But I went about machining immediately since kicker was applied. It stayed put during machining. I torched it for a minute & this time because it was thicker part ~0.5", I gave it a light whack with nylon hammer in the shear direct, came off perfectly.

So my conclusion for smallish parts CA is fine. What little experience I had removing locktited fastners with heat, it took a lot of heat but the thing is you can apply substantial force to a capscrew whereas on parts this may not be feasible without marring things, at least aluminum. I think the better failure mode is shear if that's feasible.

Clickspring has bunch of vids on this. He tends to put a lot more glue on than i did, but he also pre-grooves his plate so I suspect it may have the equivalent amount on in bonding. Both my parts were 0.001" under when I registered zero cutting the glue plate face, so guessing the CA is about that thick. Doesn't take much.

[john mills]

I  have used lock tight to hold parts on mandrels for grinding  the hole was not always very straight could be drilled from both ends and not meat that well in the middle so mandrel that would slip in the hole was good then any of the lower strength grade was used then just pressed out after the grinding was finished but i avoided the
high strength grades.parts were often wire guides for wire working machines.parts were k110 hardend and nitrided  could be 10mm hole 38mm did on outside to 28mm hole  200mm long 80mm dia out side.
always   worked for me.

[petertha]

Medium thick CA glue retention example for lathe work. This is a steel gear I had to open up from 5mm to 10mm & face one end. The pot fixture was 6061 aluminum. The gear OD was a nice snug fit on the fixture ID & also back stopped against a recess. I also drilled a relief hole in the rear of fixture to insert a drive pin once heated. My experience with releasing CA is it needs heat (in this case an ordinary propane torch) but even so may still need a light gentle tap to break the part free. I drilled the holes progressively so as not to apply too much torque to what amounts to little actual contact area. There was probably about 10 healthy drops of CA in there so it made little fillets among the teeth. And I used an accelerator to make sure it was insta-cured.

The glue is completely removed with solvent like acetone & bit of soft bristle brush.

[petertha]

And here is a thin stock aluminum piece. Chuck up a sacrificial blank, in this case aluminum. Face it in-situ. Center drill a relief (this is for the tailstock center to protrude into if necessary on thin work). Clean parts with methanol. Apply CA glue, position part using tail stock center. I like to use accelerator just to know its cured. Turn the part & release with torch heat.

[mcostello]

There is also a fixturing wax available.

[petertha]

Do you have a source link? I actually went on a bit of internet search on wax's of that sort. Maybe some of you have more experience. Seems like it is more popular with the jewelry & clock making crowd. There seem to be different varieties, maybe adhesion / hardness / melting temps. Some are shellac based, others are ?? http://www.gessweincanada.com/product-p/811-2600.htm

But in my forum lurking, seems like a lot of these same jewelry/clock people were switching to 5 min epoxy or CA glue over these waxes. Maybe availability or cost or performance? Plus I'm guessing their parts will never see much of any heat or cutting pressures from lapping or cutting/engraving vs. machining. Strength wise, its pretty hard to beat modern glues, we just want it to 'let go' when the machining is done. In particular applications like I'm showing where initial positioning & part/holder orientation in the lathe, I think wax would be more of a handful to heat to melting & then stick the part. I've seen some guys glue metal onto MDF substrates with hardware store 5-min epoxy &similarly release under heat. I think I'd go that route for more fill-in factor if required.

Anyway, another trick to store in the noggin.