Installing needle bearings on a press??

[oley55]

I am contemplating installing caged, full compliment needle roller bearings in the pivot points of an old RCBS A2 press. I am looking at the 1/2" wide B88 bearings for each of the top 1/2" link arm pivot points and a pair of 1" wide BH1016's in the 2" wide bottom 5/8" toggle.

If (a big IF) I decide to make the mods, I am worried that a 5/8" drill press (30 year old Taiwanesium) drilled hole will not firmly hold the bearing cages in place (keepers/snap rings are not an option). The bearings outside cage diameter is: 17.463 mm (0.6875"). The same concern holds true for the lower bearing with an outside diameter of 11/16".

Any machinist folks out there who can advise me on this, or is there an adhesive I could smear in the openings to hold the bearings in place (but is not permanent)? Or should I just take my pieces to a machine shop, or is this just a bad idea all together?

[elmacgyver0]

Why do this?

[SweetMk]

Bearings that "roll" are designed with the intent of some minimum rotational speed.
This movement causes the bearings to pick up, and maintain a coating of lubricant between the steel surfaces.

If you operate the press slow (which is normal) the bearings have time to "squeeze" all the lube out of the contact area,,
this allows metal to metal contact,, the contact will cause the bearing surfaces to gall, and spall,,
A lube impregnated bronze bushing is the perfect answer, it is designed for slow operation,,
Install the largest one possible, width, and diameter.

[SweetMk]

If (a big IF) I decide to make the mods, I am worried that a 5/8" drill press (30 year old Taiwanesium) drilled hole will not firmly hold the bearing cages in place (keepers/snap rings are not an option).

Any drill, high dollar USA, or 30 year old Taiwanesium, will drill a hole that is triangular (shaped like a piece of pizza)
It is just what drills do, most of the time, you do not notice it,,
and, it does not matter if you are just putting a bolt through the hole.

After drilling undersize, you need a reamer to finish the ID to be round.

[Winger Ed.]

If you have to glue something in, JB weld is pretty good.
If heated to around 450F it breaks down to a ash, and can be 'unglued' that way.

[oley55]

Why do this?

At the great risk of this thread immediately going off into the weeds, I'll politely say because my press has some wear which I believe can be resolve by installing bearings.

[oley55]

Bearings that "roll" are designed with the intent of some minimum rotational speed.
This movement causes the bearings to pick up, and maintain a coating of lubricant between the steel surfaces.

If you operate the press slow (which is normal) the bearings have time to "squeeze" all the lube out of the contact area,,
this allows metal to metal contact,, the contact will cause the bearing surfaces to gall, and spall,,
A lube impregnated bronze bushing is the perfect answer, it is designed for slow operation,,
Install the largest one possible, width, and diameter.

I had considered the impregnated bronze bushings, but I have displace steel on the top right pivot arm (possibly from inadequate lube on the pressed-in pin). The harden pin is a little shiny on top and bottom and matches the displace metal on the top and bottom of the link arm's hole. I thought that was telling me the high forces would quickly distort the bronze bushing...??? Especially since the removal of too much steel for a thicker bronze bushing would weaken the link arms. I was of the thought the full compliment of hardened needle bearings against the hardened pin would not be prone to the galling you describe. But I am for sure not arguing against your recommendation, just offering up what I was thinking.

Are there different grades of bronze bushings which can take higher pressures?

I had planned to get a solid top ram made so I can attempt bullet swaging with it. So it will definitely see high stresses.

edit added: It seems the Corbin S press uses needle bearings in the link arms and imprenated bushings for the linier movement of the rams. All links run in bearings, as does the ram (two inch-long oil-impregnated bronze bearings support and guide the ram inside its hydraulic cylinder sleeve housing). Although hard to see in the attached, those are needle bearings. However that doesn't mean they will work for my application.

[nhyrum]

Bearings like that will require (from my little bit of digging) a press fit, which means your hole needs to be within a few thousandths, with a max diameter of .010 over the bearing diameter (according to the one chart I saw). I don't think you'll be able to get that together with hardware store bits. If it were me, I'd buy a cheap reamer that's long enough to do both holes/sides in one shot, because, good luck doing one at a time from the top of each and getting them lined up.

This is just stuff I dug up on the interwebs, and my one year of engineering/machining classes I took in college almost 10 years ago. So by no means am I anywhere near close to having a decent amount of subject expertise

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[oley55]

Bearings like that will require (from my little bit of digging) a press fit, which means your hole needs to be within a few thousandths, with a max diameter of .010 over the bearing diameter (according to the one chart I saw). I don't think you'll be able to get that together with hardware store bits. If it were me, I'd buy a cheap reamer that's long enough to do both holes/sides in one shot, because, good luck doing one at a time from the top of each and getting them lined up.

This is just stuff I dug up on the interwebs, and my one year of engineering/machining classes I took in college almost 10 years ago. So by no means am I anywhere near close to having a decent amount of subject expertise

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concur on processing both holes at the same time, and based on what SweetMK says about the pie shaped drill bit hole, a reamer seems to be the only option. Altering a late 1950's early 60's press is not to be taken lightly, and I surely don't want to end up trashing an old workhorse tool/press. IF I do press ahead, a machine shop seems more and more likely for me.

[SweetMk]

Before you install the bearing, simply envision how a few needles will be under pressure, with almost no surface area touching.

It is kinda like putting your thumb on the pointy side of a thumb tack, then turn it over and push on the flat side of the thumb tack.
It all has to do with area,

The bushing has thousands of times the surface area of contact, so the bushing can be thousands of times weaker.
The bushing wins.

That is basically in all reloading press pivots, cast iron against a steel pin,, the perfect balance of force versus surface area.

Bearings win, when the rotation is fast.

[nhyrum]

I just see the bottom of the races getting chewed up. There's a lot of pressure with little movement. Needle bearings I see being better then ball in my mind. I can see bushings being better as a bearing won't have really any lubricant, but I'd worry about bushings cracking. I'm on the fence between those two.

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[country gent]

I see several issues. Needle rollers on a soft shaft under med to heavy loads will compress the shaft where the needles bear you may want to consider an hardened inner race on the shaft. Drilling and reaming the bore should make an acceptable fit. In most shops a slightly loose fit can be cured with blue or green loctite. Another consideration is the addition of grease zerks to lube the bearings. The rollers might be a improvement but comparing cost to gain I believe that simple bronze bushings will be as good at the slow speed operation. A drill Press can do a lot of work and with a reamer or boring bar can make very accurate round holes. but set up time and the operations take more set up and skill than a mill does.

[oley55]

I just see the bottom of the races getting chewed up. There's a lot of pressure with little movement. Needle bearings I see being better then ball in my mind. I can see bushings being better as a bearing won't have really any lubricant, but I'd worry about bushings cracking. I'm on the fence between those two.

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In my response to SweetMK, just edited in info from Corbin about their swaging presses and they do use needle bearings for the pivot points and their presses far exceed the pressures my press is capable of.

[country gent]

Yes but they may also use case hardened shafts with a surface of 55 rc

[oley55]

Before you install the bearing, simply envision how a few needles will be under pressure, with almost no surface area touching.

It is kinda like putting your thumb on the pointy side of a thumb tack, then turn it over and push on the flat side of the thumb tack.
It all has to do with area,

The bushing has thousands of times the surface area of contact, so the bushing can be thousands of times weaker.
The bushing wins.

That is basically in all reloading press pivots, cast iron against a steel pin,, the perfect balance of force versus surface area.

Bearings win, when the rotation is fast.

I really appreciate your taking the time to help me with this. A point of clarification my A2 (2A) press is cast steel vs cast iron, not that it matters. This link to Corbin and their entry 'S' swaging press and it shows them using needle bearing in the same location I am considering. They do however use impregnated bronze bushings for the linier movement of the ram.
http://www.corbins.com/csp-1.htm

So, for the time being I'll continue to pursue the needle bearings option and finger out the drilling/reaming options.

Again my thanks.

[oley55]

Yes but they may also use case hardened shafts with a surface of 55 rc

Granted, I do not know how hard my shafts are, but they are hard enough to not distort or mar when I drove the two pressed-in shafts in and out with a drift. I'll take a center punch to one end to see how hard it seems. These early (pre-Rockchucker) RCBS A2 (2A) presses where actually made for bullet swaging and were available with solid top half rams for that purpose. My current top ram with cut-out for the primer will buckle/collapse under swaging pressures.

[ulav8r]

Cast iron bushings would be a good solution.

[elmacgyver0]

At the great risk of this thread immediately going off into the weeds, I'll politely say because my press has some wear which I believe can be resolve by installing bearings.

I was just curious, I had never seen a press wear out with proper maintenance.
Of course I don't do that much reloading or know anyone that does.
Anything will eventually wear out if used enough.
If nothing else the needle bearings might reduce the force required to operate the press.

[oley55]

I was just curious, I had never seen a press wear out with proper maintenance.
Of course I don't do that much reloading or know anyone that does.
Anything will eventually wear out if used enough.
If nothing else the needle bearings might reduce the force required to operate the press.

I have no idea who/how this 60 year old press was maintained, but the point of wear is around the top right pressed-in shaft. Getting lube in there requires laying the press on its side or upside down and flooding it with oil/lube. It's my guess it got a squirt of oil while in the bolted down position and rarely got lube into where it was needed.

Now knowing this pivot point needs close attention, I would anticipate any future issues will be component failure vs wear related. Although I can not really feel or identify any binding, under pressure the worn link hole has to be inducing some torque to the press parts and alignment. If I am going to use it for swaging, it needs to be squared away. Otherwise it's just fine for general reloading purposes.

[oley55]

Shafts are probably not case hardened, but they are hard enough to blunt two center punches, a vintage MPC-USA punch and a Craftsman USA made punch. I was able to make a punch mark but it's a tie between tools and shaft material. For whatever that's worth.

A cursory look at the impregnated bushing and the needle bearings, it seems my reamed hole size should accommodate either option...?? If that proves true, I will likely go with the impregnated bronze bushings first. If they don't hold up, then I can try the needle bearings.