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New Guy Needs Help Learning Specs On Slip Fit Holes For Bearings

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DavidBeck

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#1
I heard this place was a good site to come to for information without judgement. I will start off by saying I am not a machinist, I own a Grizzly mill but barely know how to use it. I am working on a project where we are inserting bearings into metal and they have to be slip fit. Where my confusion lies is how oversized should the hole be? The bearing is 1/2 inch and we are using loctite 680, I have read the data sheet for the loctite and lets be honest here I am again not a machinist so those numbers are hard for me to understand. I bought a 501 reamer and was thinking it might just be the trick for the bearing to slide right in and the loctite will hold it in place. My main concerns are these
1. The bearing needs to be centered
2. There can be no outside pressure on the bearing or it will slow it down or even prevent it from spinning
3. Is there a reamer just under the 501 so the 1 would be at half?

Any help would be great, I have tried calling the bearing company but getting past the guy who answers and knows nothing has been a pain, I don't want to switch bearing companies as I 100% love this bearing.

I am also located in San Jose, CA and will be looking for a machine shop to run 100 pieces of this item once our specs are in line.

Thanks again
David
 

rgray

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#2
There all plenty of .5005 reamers. Google is your friend. amazon even has them.
 

Tony Wells

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#3
First, welcome to the Forum, David. Glad you came here looking for answers. We'll work you through this.

First, we need to know why you believe you need a slip fit, and why you are planning on using LocTite. I can only guess at this point that you want to hand assemble this without a press and yet have the bearing firmly held in place. If so, then you are on the right track. Rather than asking the bearing supplier, your better source of the required clearance would actually be LocTite. Since they make the stuff, they have done all the testing to assure the maximum holding power and the strengths and weaknesses of a chemical bond type fit vs a press fit. But we can probably get you the information, and coupled with some real world experience come up with a good recommendation.

One major factor in the success or failure is the mode the bearing will be operating in. What kind of load will be running in it? Are there going to be forces in a linear direction? What exact type of bearing are you planning on using here? Is the shaft (or whatever is running in it) also a slip fit, or is it to be pressed? Is there only one of these bearings on the shaft or is there a pair (or more) that will need to be aligned? What temperature range will this assembly see? Or is the shaft stationary and the bearing fitted into a piece that will be moving?

I guess what I am getting at is that there are numerous factors that will determine the best way to solve this problem. I'm sure I didn't cover them all, and other members here will come in and ask more questions.
 

DavidBeck

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Thank you so much for the reply, the item it will be inserted in is a hand fidget toy. So it will be inserted and then buttons will be placed over the top of the bearing and screw together, you spin the body and the buttons stay stationary while the bearing spins the body. The reason we decided slip fit is because the bearing being so small tends to bend very easy. As for how it spins, you can do one handed spins with a finger or table spins where it sits flat or a two handed spin where it will have some forces. I read on loctite the 680 is up to 4000 psi.
 

Tony Wells

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#5
OK. The 0.5010 size is fine for that. The most off center it could be is 0.0005. That's not much. It would take more than that small error to cause balance issues at hand speeds. And it will be snug, with the loctite in there so hand assembly will be only a little difficult in that it will have to be pretty straight on insertion not to hang up. Once you get it in there, it would be best to let the loctite set up while the assembly is horizontal if possible. That should minimize even the potential 0.0005 error you might see. Or not see. Of course, it would be prudent to do a test run and see if the reamer will cut true to size. And please be aware that reamers, although they are used to control size closely, cannot and will not correct for location. If you have in mind simply drilling a hole and running a reamer thru it, you might end up on size, but most likely not, and almost positively not on location. That's because they will follow any error in the location of the drilled hole. Your best bet and surest way is to drill it under, bore it still under but on location, then ream for size.
 

DavidBeck

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#6
I won't be doing any of the work except assembly, the machine shops I have talked to aren't familiar with what I am trying to do, I just want to give them the best solution I could come up with which was for them to ream with the 501, I had heard about half sizes in reamers and had wondered if I should look into that then my margin going up would also be ok?
 

Tony Wells

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#7
Yes. If you try to run them at 0.5005 it will be noticeably more difficult to insert the bearing, and it isn't necessary for them to be that tight. Of course, there has to be a mfg tolerance stated in any case. If you specified 0.5010/0.5005 you would be in ok shape, but the closer (tighter tolerance) you spec, of course, the more cost you will incur. I certainly wouldn't want them any tighter than 0.5005.
 

DavidBeck

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#8
Wow you are awesome, I greatly appreciate this . Now is there a resource for finding local machinists to my area?
 

DavidBeck

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#9
Also since I will ream with the 501, what should I call out as the tolerance for the hole?
 

Tony Wells

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#10
I don't know any resources specific to your area. It's not impossible to find someone here who might want to tackle it. We do have members in your area. Give it a day or so, and with 18k members here, someone may well chime in with input. Not all here are hobbyist. Some of us do this for a living.

As far as tolerancing for the hole, I would stay with 0.5010/0.5005. That is a reasonable tolerance for a reamed hole and shouldn't drive the cost up. I realize the tolerance zone is only a half thousandth, but for a reamer, that's completely feasible.
 

DavidBeck

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I am not apposed to working with a machinist out of the area, to be honest prices would be better than my area, even with shipping. I need to find someone who is willing to work with someone who doesn't know about machining but can still relate to what I am trying to do. I know I want to do 100 pieces and 200 lathe pieces.
 

Tony Wells

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#12
Do you have finished drawings to present for quotation purposes? You will need them for this. Otherwise, by rights, the shop would be in line to charge for helping you work through finalizing the dimensions and tolerancing.

Let's see who else runs across this thread. There probably are a few who would like to make a little "side money".
 

JimDawson

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#13
Drawings or even rough sketches would be good. Many of our members are used to working with back-of-the-envelope ''drawings''

The tolerance Tony suggests seems reasonable, well within the range of a reamer. Without having a bit more idea of the part shape, I couldn't offer any other suggestions.
 

DavidBeck

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#14
I have DXF files and pdf of the first version, we have artistic renditions of the next versions based off our first. Am I allowed to post my contact info or ways of direct messaging like via facebook?
 

JimDawson

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We generally recommend not posting personal information in the general forums, just for security and spam reasons.
You can post drawings or pictures if you are not worried about showing proprietary information.

You can contact any member by clicking on Contact under their name. This opens up a new window and is a more secure method of communicating with members as it is only visible to to the conversation participants. This would allow you to pass personal information along with reasonable security.
 

DavidBeck

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#16
Ok well anyone who considers them self's talented machinists who can work on a bigger scale please contact me, I am looking for a new shop to move forward with.
 

JimDawson

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#17
One question that comes to mind is what materials need machining?
 

DavidBeck

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#18
Stainless steel, brass, copper, titanium and some hybrid metals which are the same as damascus and titanium.
 

JimDawson

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#19
That makes it more interesting. :cautious::eek 2:
 

JimDawson

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#21
David I sent a PM to you.
 

dlane

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#22
If I wasn't moving I'd do those for you, but all my equipment is broke down and ready to load up and move Tuesday, as I'm in San Martin rite next to SJ, I'm moving 187mi north
 

stupoty

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#23
As the matirials sound expensive and slightly exotic you will probably need to make a prototype of some kind or at least experiment with the reaming and machining processes on some off cuts of the matirials to be used.

Just as an aside, their should be no problem with a press fit of suitable size for a smaller bearing as the size is related to the diamitor you are press fitting. Theirs a section in marks handbook on fits at diferent diamitors very handy stuff.

The loctite will be easier though as your tolarance can be looser and the loctite "should" center the bearing in the bore by surface tension.

Ramble over.

Stuart
 

DavidBeck

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#24
I have a working proto that was made, and when I reamed it to a 501 the performance greatly increased which I was happy about, the down side I put it into a vise and went a little too tight and bent my proto. I spent a few hours and got it as close to straight again and was able to get an extra 1.10 seconds out of the bearing. for spin time.
 

tq60

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#25
First many folks here can make it for you but you have the engineering responsibility to insure what you think you want is what they think you mean.

If the bearing sales guy cannot help then seek out the bearing manufacturer and discuss your needs with them and they can provide a very detailed data sheet specifying the parameters for fit and tolerances.

Include that in your drawing and note the drawing to reference that sheet.

For a hand operated device speed and strength are not that much so a great amount of options there


Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 

stupoty

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#26
I have a working proto that was made, and when I reamed it to a 501 the performance greatly increased which I was happy about, the down side I put it into a vise and went a little too tight and bent my proto. I spent a few hours and got it as close to straight again and was able to get an extra 1.10 seconds out of the bearing. for spin time.
Always anoying when you squash somthing in a vice, i think every ones done it once or twice (or more :) ) brown paper or soft metal shims can be good to improve the grip on a part with the same clamping force.

Stuart
 
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