Weak but reliable metal glue?

I am still struggling with making an encoder adaptor that would go into the top of my spindle (spindle is hollow, with a 26mm hole), and
have a 3/8" shaft protruding on top to mount the encoder disk.
After a few things that did not work, I am settling on simply making this adaptor out of 12L14. It should be easy to make on a lathe. I am thinking how to avoid making it "expand" but just stay in place without expanding.
Whet I would like, I think, is make it fit the spindle precisely, yet without any significant force involved (that is, not press or interference fit), but use some weak glue to hold it in place. This is so that I would pull it out easily when necessary.
Would anyone have any suggestions as to the glue.
Thanks
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wrote:

Why don't you want it to expand? It seems that a couple of rubber plugs, sized very closely to the shaft, could compress just a little - maybe .010 or so - and give a nice fit. Of course, I don't think you ever said (or I never caught) how deep the hole is.
Most hot-melt glues release pretty easily and are alcohol soluble. Solid-surface countertop guys use it to glue on clamping blocks which they later release by wetting the edges with alcohol.
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On 12/16/2010 06:24 AM, rangerssuck wrote:

An O-ring, set into a groove in the adapter?
Locktite has something, if you can get their attention for a one-off (Locktite _always_ has something, even though I've heard complaints here about their technical support slipping).
If you make the adapters out of Nylon, Delrin, or similar kinda-springy, kinda stiff plastic, you should be able to achieve a press fit that'll still pull out by hand. If that's not stiff enough, maybe bushings?
--

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Wescott Design Services
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I think I offered that idea but thanks for the seconding.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
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wrote:

Why don't you want it to expand? It seems that a couple of rubber plugs, sized very closely to the shaft, could compress just a little - maybe .010 or so - and give a nice fit. Of course, I don't think you ever said (or I never caught) how deep the hole is.
Most hot-melt glues release pretty easily and are alcohol soluble. Solid-surface countertop guys use it to glue on clamping blocks which they later release by wetting the edges with alcohol.
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Along the lines of hot-melt glue, there is pine-tar or coal-tar pitch. Glass lens blanks are attached to tooling during grinding with this stuff. It melts at 140 to 170 deg. F and sticks tenaciously to metal and glass. Parts can be separated either by melting again or by cooling and giving a rap with a hammer. Cold residue can be chipped off or removed with solvent. If the parts get hot it will start to flow and creep so watch out for that. You can find small quantities at online sites that sell amateur telescope making supplies such as: http://www.willbell.com/ATMSupplies/ATM_Supplies.htm Look for "blocking pitch."
You can also use rosin in a similar way. It is more brittle than pitch but creeps less at elevated temperatures.
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wrote:

If you cut a slightly oversized fine thread on the adapter it will be fairly easy to get a light to moderate press fit since the threads will crush. If you cut too deep you can pad them with fishline. Or you could squeeze it oval or better triangular.
Some of the Loctites release easily when heated.
I was the stuckee nominated to salvage a batch of prototype assemblies after extra-strong Loctite had accidentally been applied to screws in brass inserts molded into plastic. The task was easier than the assigner expected (hoped?) when I heated the screws with a big mutha soldering iron.
jsw
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"Glyptol". It's the glue of choice in military stuff for "just holding on", but still easily crack-able.
It's just thick nitrocellullose lacquer. For your purposes, Ambroid model cement or Duco cement should work.
Make sure both surfaces are immaculately clean. This stuff just-only sticks to metal.
LLoyd
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Wild idea. Turn a groove in it and insert a neoprene o-ring? Not good enough?
Loctite green is a sleeve and bushing locker. Takes heat to remove. I have used it with good success for press fit water passage adaptors on engines.
Weak metal glue? Machine your adaptor with a flange so it rests on top, and put a thin layer of silicone household adhesive on top. Make the flange square or hex shaped so you can break it loose easily with a wrench. The silicone will break loose easily, and peal off the parts with your fingers. (has be be clean and dry to work) Worried about oil later? Use an engine gasket silicone.
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Ignoramus6780 wrote:

Can you post some close-up pics of your mill head from all accessible locations, access ports, etc? I'm pretty sure we can come up with a better solution if we can see in detail the possible options.
I'm pretty sure that you would be better off with an inductive pickup of a gear than messing with a shaft encoder. You don't need a lot of resolution, and even if the gear you pickup from has different ratios in high/low ranges, you can easily account for that on the software end.
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Ignoramus6780 wrote:

On the shaft idea, how about determining a screw thread that has a tap drill diameter of 26mm (or close to that), and tap an inch or so of the spindle. Make an adapter with that thread for a couple inches then stepping down to your 3/8" shaft size. Thread the adapter into the spindle and follow with a backup nylock nut.
No matter how you connect to the spindle, I highly recommend you use a separate bearing supported shaft for the encoder and a flexible coupling to your spindle adapter.
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Asked and answered.. how many times now?
How many more times are you going to ask about the same situation? If the answers that you were given previously weren't any good, then ask somewhere else. Maybe you've wondered why different folks have suggested you're a troll.. here's why.
That lathe of yours has been sitting there for about 2 years (or more?).. so make a part, just as others have suggested before.
If you're still reluctant to use the lathe, write a prog for the mill for making the part.
A simple part that adapts a hole to a stem isn't a complicated issue.
Use plenty of coolant.
--
WB
.........


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You must be on another planet, Bill. Iggy is anything BUT a troll, and I can't remember anyone suggesting he was, except years ago, when he first started learning this craft.
He has questions, yes. But he also actually DOES things, and when they don't work, he asks again.
Have YOU retro-fitted your own mill from scratch? Hmmmm?
WTF?
LLoyd
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On 2010-12-16, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

I was admittedly going in circles, but that is not quite the same as being a troll. I wanted to do it right.
I ended up making an adaptor on my lathe.
After installing it and reconfiguring EMC2, rigid tapping kind of, sort of works right now, but there are many loose ends that I need to figure out.
For example:
1) Following errors when in straight gear (not in back gear). Perhaps this is because of wrong base period of the main thread, or something else.
2) In back gear, forward means reverse and reverse means forward, and I need to find a way to fix that. Right now rigid tapping in back gear is ridiculous: The spindle runs CCW and goes down, then reverses and goes up while spinning CW. I, obviously, need the opposite, unless I use a left handed tap.
If I solve issue number 1, I could tap small holes, perhaps up to 5/16 NC, without going into back gear. It would be scary to watch, but will be just fine.
For up to 5/8 NC, I would need a back gear.
3) I still would like to somehow double check the index pulses vs. encoder counts.
i
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Ignoramus6780 wrote:

On our Bridgeports, the direction of rotation is not linked to the mechanical, IN or OUT of back gear. so you can always run the spindle in any direction regardless of "speed range". I guess the power downfeed would be a problem though. :-) ...lew...
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On Series II Interact 2, back gear reverses the rotation.
This would not be a problem, ordinarily, as I could command the mill to run "in reverse" when drilling, milling etc and it would be great. However, when rigid tapping, the control wants to run the spindle "forward", which in back gear actually means reverse. This is the problem with rigid tapping.
i
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Ignoramus30138 wrote:

You need to configure EMC2 to reverse it's spindle direction control depending on the selection of the high/low gear range.
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Yep. I think that I can do it with some and2 elements.
i
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    [ ... ]

    I believe I suggested back when you were early in this project that you set up a switch to sense the lever in the back-gear position, and use that to either tell EMC2 to command the opposite direction, or simply have it work a relay to interchange the forward and reverse pins on the command to the VFD.
    Admitedly, I was not thinking of rigid tapping -- but things like burning out end mills or drill bits because you are running them backwards.
    Good Luck,         DoN.
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That's what I ended up doing.
i

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wrote:

Hey - I just had another idea!
Pretend you're working on a deadline, and the glue absolutely, positively has to stick forever. You're pretty much guaranteed that it will fall apart easily.
Loctite 290, which is meant to wick in to assembled threads, breaks free pretty easily. It keeps fasteners from vibrating loose, but yields easily to "normal" wrenching.
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