[PSUBS-MAILIST] Press Fit

Fri Mar 30 05:41:42 EDT 2018

 Alan, I rarely can machine to the tolerance your talking about.  I cheat and get very close then finish with a real good flat file then polish the part with progressively finer wet and dry sand paper.  I will go right down to 2000 grit some times..  I am not sure if it is me or the lathe.Hank
    On Thursday, March 29, 2018, 8:43:07 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Thanks Hugh,
I'll have a look in the shops after easter to get a handle on whats available.
On the net there seems to be quite a range in prices from about $30- to thousands.
Always enjoy visiting your premises & seeing the Q-sub and would appreciate
any advice with this precision machining. 
How is the Q-sub going?
Cheers Alan

Sent from my iPad

> On 30/03/2018, at 2:03 PM, Hugh Fulton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 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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