[PSUBS-MAILIST] Press Fit

Thu Mar 29 21:03:05 EDT 2018

Alan,  You are really brave to try and measure that way.  Even tele gauges
are hard unless you have a lot of practice with them but not with calipers.
You have to use them with an outside mic to give you a fighting chance as
you have just found out.  You should be using a bore Micrometer or at least
inside mic for bearing fits.  I think you should pay a visit out to our
workshop if you are planning on doing that sort of thing in future. So much
is in the feel using instruments.  CRC do a freeze spray for that sort of
thing as well.  As the guys say get the manufacturers recommendations.  The
bearings are not universal as they come in different clearances such as C3
or C4.   Hugh   

-----Original Message-----
From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org]
On Behalf Of Alan via Personal_Submersibles
Sent: Friday, 30 March 2018 9:49 AM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] Press Fit

Thanks for the advice guys.
The bearing diameters are 35 & 24mm.
I went to a lot of fuss last time I did this & ended up having to use
loctite as the last pass on the lathe took too much off.
Emile, I will shoot for .02-.03mm & see how that goes. Have found other
advice saying .03. But found a lot of confusing information googling.
I was intending to heat & freeze parts prior to pressing.
Hugh, I have been using inside callipers & measuring  off these with the
digital callipers.
The digital callipers are on the cheap side so may upgrade them & as you
say, purchase telescopic gauges the right size.
Also on my radar is a 10 ton hydraulic hand operated press, as I am also
press fitting the two end sections of the thruster in to a tubular middle
section. I am figuring that with epoxy in the press fit, screws & an epoxy
paint finish it should be water tight without o-rings.
Cheers Alan

Sent from my iPad

> On 30/03/2018, at 8:42 AM, Hugh Fulton via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
> 
> Alan,
> What diameter is the bearing?
> As the guys are saying it is a real test of your machining accuracy.  
> Do you have a micrometer and telescopic gauges the right size?  If you 
> are relying on digital calipers you are playing with fire.  The answer 
> to your question is yes you can push the bearing in with the tailstock 
> but they don't have much push.  You can use a vice as well if it is in 
> good condition.  I suspect you are talking about something that is 
> possibly only 30-40mm.  It is very easy to over machine but you can use
Loctite if you want to.
> Suggest you  try a bit of aluminium bar as a test piece first.  Easy 
> to machine it off after or push it right through.
> Hugh
> 
> -----Original Message-----
> From: Personal_Submersibles 
> [mailto:personal_submersibles-bounces at psubs.org]
> On Behalf Of Alan via Personal_Submersibles
> Sent: Thursday, 29 March 2018 10:33 PM
> To: personal_submersibles at psubs.org
> Subject: [PSUBS-MAILIST] Press Fit
> 
> Hi,
> I'm wanting to press fit a bearing in to my aluminium thruster housing 
> & wondering if I could make a tool slightly less in diameter than my 
> bearing, fit it in the lathes tail stock, & wind it in to force the 
> bearing in to the press fit.
>  I have heard figures like 500lb force being used for press fitting, 
> which I won't get winding the tail stock, & probably don't require as 
> there is not a lot of dynamic force on the bearing.
>  I imagine there will be a lot of trial & error involved getting the 
> bore to the right diameter, & this method will allow me to keep the 
> work in the chuck & keep doing fine passes until I get it to the right
diameter.
> Any thoughts or experience with this thanks.
> Alan
> 
> Sent from my iPad
> 
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