Do you have a go-to retaining compound for cylindrical fitment applications, such as for bearings, shafts, and similar
I bought a mechanical kit, and it comes with a bunch of tapered roller bearings and cylindrical shafts. It also has a couple of aluminum pulleys.
One of the recommendations is that the bearings be seated with retaining compound. So, I took to Google and oh boy there are options.
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Retaining compound is basically an adhesive that fills the gap between parts, in this case cylindrical parts. It helps keep things from jostling when things are rotating and moving around.
I’ve been using collars and similar to keep bearings from moving around. Apparently retaining compound can help simplify things.
There are different formulations depending on the gap between parts. One is for slip fit, another for press fit. Another is described as being for oily loose-fitting parts. Some retaining compounds are thin, others are thicker. You can get higher temperature-resistant compound.
The options seem to change a little depending on whether it’s for new application or repair.
“Primer” is recommended for inactive metals such as aluminum and stainless steel. From the datasheet, Loctite’s primer is between 99% and 99.9% acetone. Can’t I just use acetone?
This is one of the bearings that needs to be seated inside an aluminum housing. It’s going to be a press fit, and others are a little looser. The shaft that goes into this bearing, for example, will be a slip fit.
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So far I think I selected on Loctite 680. I was then convinced that I had it wrong, and cycled through 3 or 4 other retaining compounds until I came back to 680. I briefly looked at Permatex, but haven’t taken a closer look yet. There are other brands, too.
Working with other types of parts, such as shafts with keyways? There are different options for that.
I wish I were the type of person who can just say “eh, SuperGlue will work almost as good,” but I like to understand the options. This won’t be the first time I’ll be working with larger bearings.
That’s also the purpose of the kit, to help me learn what I don’t know so that I make fewer mistakes with upcoming scratch-built projects.
The best approach would be to call Loctite technical support and give them some criteria. I’ve tried to work through their online resources, but they’re messy and seem more aimed at manufacturers who will be buying gallons of the stuff. The biggest problem is that there are multiple parts, all different sizes.
It seems like a good idea to choose a general purpose go-to, and to later on consider other formulations if need-be for critical outlier applications.
So, what’s your go-to retaining compound? Any tips?
I’ve also been trying to figure out what I need for pressing bearings into place. Automotive and bike tools might do the trick, and I should be able to use some of them with my small arbor press. I’m just looking to avoid hammering things into place.
Nate
Sockets and sections of pipe if the socket is not long enough for pressing bearings. You can tap them in or press them. As for the compounds, I wouldn’t trust them to hold. You need collars imo or some other way of a mechanical fastener.
Stuart
In most cases for this project, there’s a shoulder or lip. In others, collars or clamps might hold the shaft, but not specifically the bearings, leaving them technically unconstrained.
I added a photo of the largest bearing. I definitely don’t have sockets that large, or steel pipe. There are 6 sizes of bearings. The bearing mounts all seem to be press fits, and shaft to bearing fitment slip fit.
Nathan
I think most of that was designed around chemistry that wouldn’t hurt the metallurgy. Ca glue might well be ok too. Many times once fully assembled the bearing won’t move anyway. So temp measure at best.
However I’m most familiar with locktite brand and would suggest any countpart competitor is probably good enough too.
Pressfit situations I’ve never seen it used and also do you have an arbor press
Doresoom
Pay attention to the fit between your shaft OD and bearing ID. Different retaining compounds will have different specs on what they’re designed for.
For example, Loctite 638 is meant for .006-.010″ gap fill, while Loctite 648 is only good for up to .006″. The two have different viscosities, with the thicker one being able to fill larger gaps.
Since most retaining compounds are anaerobic cure, you need to make sure they’re capable of filling that gap or they won’t cure properly.
Stuart
Would it be accurate to conclude that a more viscous compound can work on smaller gaps but might be difficult to work with? Specs charts typically have the max gap fill.
From one of the selection charts I found, the 680 has higher viscosity than close-fitting parts compounds (such as 603), but far less than others such as 638.
Ideally, I think one from the loose-fitting parts category (e.g. 680) and one from close-fitting (e.g. 603 or 609) would be best. I’m trying to save money, waste, and having to choose on a case by case basis most of the time.
MM
I’ve used the thicker compounds on smaller gaps before. It works fine, though it can be messier to apply the compound. If the gap is small then the thinner compounds will often wick into place with capillary action, sort of like how “green” formula threadlocker works, which makes it easily applied. However you can use the more viscous ones on thin gaps too, though you might have to apply to both the shaft and the ID of the bearing before installation an then wipe away the excess. On the other hand, the thinner compound is useless on large gaps.
Doresoom
MM summarized it well. You’re going to make more of a mess with thicker compound in a close or press fit.
That’s something to avoid in a production environment where it’s going to cost extra time for every assembly, but shouldn’t be an issue for your one-off project.
MM
My go-to is Loctite #620. I don’t use primer, I just clean the parts with whatever solvent I have at hand. (Acetone, brake cleaner spray, etc). As I understand it the “primer” isn’t a primer in the traditional sense, it’s just a degreaser to make sure there is no oil on the surfaces that could contaminate the bond. I’ve used #620 on everything from tiny 1/8-in diameter shafts up to 5-6″ stuff on industrial machinery.
As for tools for pressing bearings: I use sockets & sections of pipe like Nate mentioned. Also, “bearing seperators” that are typically used with pullers can sometimes be useful depending on the situation. If you’re working on tapered roller bearings then get a race driver set, these days there are lots of cheap ones available and that is a tool where you don’t need to spend premium money, my Harbor Freight set has lasted me many years. If you’re replacing a bad bearing then you can often re-purpose or modify the old one to make an installation tool for the new one.
Don’t forget heat as your friend for bearing installation if you are dealing with tight fits. Bearing heaters are a thing, you can also DIY it with a portable hotplate, old toaster oven, or a torch. Don’t overheat the bearing, but thermal expansion can enable you to slip a bearing over a shaft without much if any pressing.
If you need to remove bearings from a shaft then a MIG welder is a handy tool for this. Cut off the outer race & remove the balls/rollers and the cage, so there’s only the inner race left on the shaft. Quickly lay down a heavy bead of weld on the race. Don’t weld it to anything, just put a bead on it. Very often, the heat from this will cause the race to expand allowing the race to slide right off the shaft while it is still hot. I learned this from an old-timer diesel mechanic and it’s been very handy. It’s quick and it doesn’t risk damaging the shaft, as can easily happen if you’re trying to cut the race off with a torch or a grinder.
eddiesky
Also cold can work with shrinking a part to fit then normally warm up and fit. I’ve gotted dry ice from a supermarket for a one time fitment without having a hydraulic press. Watched CEE on Youtube. Ofcourse there is also This Old Tony…
MM
Thanks for mentioning that. Back when I managed a university lab we had liquid nitrogen on hand so I often used that for cold-shrinking. I no longer have such convenient access to LN2 so I hadn’t really thought about cold-shrinking since, but you make a very good point about dry ice: it is widely available and works well for this.
This also brings to mind a mechanical solution: keyless bushings like Fenner Trantorque are an option too. There is no adhesive or pressing required, and the assembly is very easy to take apart with thin pattern wrenches.
Kyle
I’ve had some success with Vibra-Tite products. They offer many of the same sorts of products as Loctite and Permatex, but often much cheaper and their products are for the most part made in the USA. It’s professional quality stuff, not simply a discount import product of unknown quality.
I first used some of their 542 large gap retaining compound and 611 activator/primer to replace bearings on some commercial lawn equipment where a mower deck spindle bearing spun and damaged the bore it was set into. That’s rough service, but it worked admirably. Came in handy for several other projects since where fitting bushings and bearings into less than perfect bores.
Even if you have shaft collars, snap rings or other mechanical retainers those generally just keep the bearing from falling out of place. The benefit of using a chemical retaining compound is that it keeps the bearing from spinning on the shaft or in its seat. I use retaining compound for most press fit applications, because of that press fit ever slips it usually means major damage.
Matt_T
I use 609, 680 and Plastic Steel depending on how loose/worn the fit is. But I don’t generally use anything on a press fit. Also normally only use retaining compound on the bearing to bore not the shaft.
I use primer if the metals require it or if I need it to set up faster. Not sure if you’re trolling with the straight acetone comment?
For press fits I’ll freeze the bearing first if time permits. I use brass drifts, sockets, steel donut plates or maybe the old bearing to drive the bearing in. Sometimes use threaded rod to draw the bearing in rather than hammering.
Stuart
Thanks!
Regarding acetone, I’m not. After seeing some online posts where people said they skip the primer and use acetone, I looked at the safety sheet.
Looking at another SDS (I can’t find the one I saw yesterday), Loctite’s 7649 primer is 80-100% acetone and 0.1 to 1% 2-Ethylhexanoic acid. It’s described as a cleaner and adhesive activator, suggesting it accelerates curing but perhaps doesn’t necessarily surface-etch or treat mating surfaces.
Online user accounts: “I just use acetone.” SDS: “mostly acetone.”
I try to avoid single-purpose chemicals as much as possible.
Fabrik8
Lots of primers use a volatile solvent like alcohol or acetone as a vehicle for the active ingredient.
Using the solvent but not the active ingredient is…. just maybe acting as a degreaser or dispersant. Leave out the metal alkoxide or silane or whatever chemical is actually doing the work is…. not particularly useful.
If you need a primer or adhesion promoter, and you just use the vehicle, you likely don’t actually need a primer or adhesion promoter.
Stuart
Thanks, that makes sense. Maybe some users are dealing with other metals that need a cleaner and not necessarily activator.
Nathan
I was also going to ask what are you making? What I might do for the center bearing of a prop shaft is not what I would do for a say lathe where it needs to be dead on center and wobble free
Stuart
This project? Robot arm kit. After that? I have a bunch of ideas I want to explore, but I felt I needed a springboard to get a feel for tested-and-mature mechanical design and control before tackling my own from scratch. Long-term, maybe a scratch-built go-cart as an example.
Jerry
I have had good results with both Loctite and Permatex brands, but I’m sure others would work well. As others have said, I do not have a single ‘go to’ compound, but rather get the stuff designed for my uses – do I need maximum strength, does it fit tight or loose, will I want to be able to take it apart easily in the future, etc.
As to the ‘conditioner’, from my experience, anything that will clean down to bare metal and not leave a residue that will affect adhesion will work, acetone will be fine. For an occasional small project, nail polish remover is good – most are just acetone (read the label and get one that is acetone) and they come in convenient storage bottles, often with an applicator brush.
Ray
I encourage you to read Kevin Cameron’s “The Ins and Outs of Ball and Roller Bearings.” The article can be found here, https://www.cycleworld.com/blogs/ask-kevin/motorcycle-ball-and-roller-bearings-explained/
Dave P
Loctite or Permatex. Just read up on the different strengths and use the appropriate one.
Superglue? You’ve GOT to be kidding…. Good that you thought better of that.
John
I think you’re overthinking this (nothing wrong with that of course). We just get a bottle of green stuff from the supply house, it’s some generic version. Never had an issue with any of the bearings we’ve put in with it. The most important thing is making sure the surfaces are clean and you install them correctly.
Stuart
ToolGuyd exists because I overthink things. I learned a little, hit a wall, shared where I was at, and learned much more.
These are like $17 a bottle for 10ml. I’d like avoid mistakes. There’s no real place local to me where I can get some quick advice, and my criteria seemed too fluid and broad to call for free product selection help.
chip hershberger
I use a crockpot with olive oil for the bearing s (female) to expand with heat,and small shafts in a zip lock bags in the freezer or an ice chest is possible.
This keeps contamination from food ,and avoids confrontation from the significant other.
Also a preheated part in the oven will cure paint very quickly, for this i have a dedicated toaster oven for small parts.
Obviously this doesn’t answer your question.
My thought is the absence of contaminants, should allow adhesion.
Although I use 2-1 primer-glue for pvc,why risk it?
Bob Margraf
Will Loctite 660 help a worn spline shaft
Stuart
You might want to double check with Loctite – they should be able to recommend application-specific compounds.