Author Topic: This is not a Cowells lathe!!!  (Read 6680 times)

Online steamer

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Re: This is not a Cowells lathe!!!
« Reply #15 on: November 24, 2013, 08:49:46 PM »
It's also where hand scraping has an advantage.....It's hard to get into trouble very quickly hand scraping , because it is a slow deliberate process.

Dave

"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Tin Falcon

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Re: This is not a Cowells lathe!!!
« Reply #16 on: November 24, 2013, 09:07:19 PM »
A couple thoughts with working in dovetails. First make sure your master side is straight then the other side parallel.
When I converted my little mill to cnc I fought to get the y axis  smooth ultimately found the gib was the problem  made a new gib it was different machine or at least like a new y axis.

if the dovetails are worn and tapered in different directions thing could be interesting.

Also cute little jewel of a lthe. never heard of a tea tray lathe before and a handsome tea tray it sits on indeed.
Tin

 
« Last Edit: November 24, 2013, 09:10:41 PM by Tin Falcon »

Offline John Hill

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Re: This is not a Cowells lathe!!!
« Reply #17 on: November 24, 2013, 10:14:58 PM »
I went to my shed this morning and attacked the bed with scotchbrite pads and kerosine/CRC.

As far as I can tell there is no 'rocking' of the front dovetail with the gib removed presumably indicating the dovetail is not hourglassed or barrel shapped.

After a cleaning I sprinkled some graphite on the slide areas and rubbed it in.  Should the slide surfaces be shiney smooth or matt?

It seems to be much better, almost working.

Online steamer

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Re: This is not a Cowells lathe!!!
« Reply #18 on: November 24, 2013, 11:18:54 PM »
John,

Do you have a bit of high spot blue?   Might be worth a mark up to see.   But you must be careful and deliberate to get a meaningful answer.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online steamer

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Re: This is not a Cowells lathe!!!
« Reply #19 on: November 24, 2013, 11:24:00 PM »
The other thing to do if you don't have blue, is to clamp a straight edge on the top of the saddle parallel to the long axis of the bed.   While tramming it in, mount a dial indicator on the bed, and sweep 1 edge while traversing the saddle with the leadscrew...IN ONE DIRECTION ONLY.     Once it is dead parallel, check the parallelism while moving the saddle in the other direction.  Ideally, you should get the same answer....though I suspect it wont be....but ....then you will know.


Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline John Hill

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Re: This is not a Cowells lathe!!!
« Reply #20 on: November 26, 2013, 07:26:39 AM »
I have got the carriage moving OK by careful cleaning and adjusting of the gib.  I also put a bush in one of the back gears that was wobbling on the shaft,  that job could have gone better but now the wobble is only there if you look for it.

 I also got the end play out of the spindle by fitting a shim washer, it was stiff when I got it assembled but it freed up after a few minutes running.

The power feed works nicely now but the little gears are still only nubs of brass.

The tailstock is a surprise, it has no internal taper and is threaded the same as the spindle, is that usual on small lathes like this?