Author Topic: tried my lathe today (Read 14102 times)

colin563 · « **on:** October 13, 2009, 01:29:22 PM »

its a chester 9x20

just trying my lathe today as i just got the diamond tool holder this morning

the finish on mild steel compared to my mini lathe is 1000 times better it doesnt look like a rat has been nagging on it

my question is why would the finish be better by hand than using the power feed

when using the power feed it gives a sort of threaded look to the finish

why is this ????????????

Darren · « **Reply #1 on:** October 13, 2009, 01:30:53 PM »

Uh oh, that's the problem I had with my mini lathe, much better if you didn't use the power feed.

jim · « **Reply #2 on:** October 13, 2009, 01:35:06 PM »

sounds like feed is too fast

colin563 · « **Reply #3 on:** October 13, 2009, 01:36:50 PM »

im feeding it faster by hand than

its feeding under power

thanks colin

Darren · « **Reply #4 on:** October 13, 2009, 02:14:47 PM »

Is it a mirror of the lead screw, same pitch but a faint pattern?

colin563 · « **Reply #5 on:** October 13, 2009, 02:37:58 PM »

i cant see what the pitch is as its so faint

i think ive found the problem in the quick change box a shaft with nine gears on

and either side of them is a brass type bushings the side near leadscrew has a small amount of play

but the other side has about 2mm of movement in the shaft

would this be what is causing the finish

colin

Darren · « **Reply #6 on:** October 13, 2009, 02:43:04 PM »

Sorry Colin I really don't know what the problem is as I never got to the bottom of it. John (Bogs) did an awful lot of work to my lathe to straiten the banana and carried out some hefty improvements.
The pattern problem was very much better afterwards, but it's still ever-so-faintly present.

Gerhard Olivier · « **Reply #7 on:** October 13, 2009, 03:47:29 PM »

Colin somthing to try

Have to appolgise as dont know all the right names so will try to explain. The problem sometimes is the the bed far side and under has no lube so it sticks and build power and then jumps again and again.

Try first to rub oil along lathe bed- far side but under (bottom of the) if slight improvement but not enough then reset the allan bolts that set the tension on the sadlle (same place) and test on several place on the bed (near headstoc /middle and far from headstock).

Please if somebody understands what im trying to say put it in proper terms.

Gerhard

colin563 · « **Reply #8 on:** October 13, 2009, 04:05:32 PM »

thanks for the reply i will try that in the morning

but im going to order the two brass bushes and clips they seem to have to much play in them

thanks

colin

sbwhart · « **Reply #9 on:** October 13, 2009, 04:16:30 PM »

Colin

Have a look at this site on how to set up your lathe it may help, it could be your lead screw not set up concentric.

http://www.mini-lathe.com/

Hope it helps

Stew

tinkerer · « **Reply #10 on:** October 13, 2009, 04:57:02 PM »

Are chips coming off under power or curls? Are chips coming off manually or curls?

colin563 · « **Reply #11 on:** October 13, 2009, 05:10:36 PM »

its curls coming off

the more i think about it

the bushes cant be helping with 2mm play in 1 side of it its up and down movement not side to side

i think the best thing to do is get the new bushes from chester first and see how it cuts then under power

it cuts great feeding by hand virtually a perfect finish on steel

thanks colin

Darren · « **Reply #12 on:** October 13, 2009, 05:13:26 PM »

Quote from: colin563 on October 13, 2009, 05:10:36 PM

it cuts great feeding by hand virtually a perfect finish on steel

If you can cut steel so well that should just about cover everything you'll throw at it

colin563 · « **Reply #13 on:** October 13, 2009, 05:18:51 PM »

it just would be nice to get the power feed working right

darren i enjoyed your tip on the 4 jaw chuck

colin

tinkerer · « **Reply #14 on:** October 13, 2009, 05:25:18 PM »

I was thinking if there was any slop in the lead screw, it would tend to chip more than curl, but I imagine it would depend on the amount you were removing. Have you tried removing .001 under power then .001 by hand? A difference would verify the lead screw and not some anomaly with the compound, cross slide, carriage or tool holder. That may be the dumbest thing you ever heard and another of the dumb things I have said, but it makes sence to me.

CrewCab · « **Reply #15 on:** October 13, 2009, 05:35:04 PM »

Colin, I'm glad your getting a good finish on steel, that was the main objective I recall

........ I would have thought feed rate was the first point to address ...... but you seem to have eliminated that. Are you using any coolant / lube plus ......... a light cut on the final pass should help the finish.......... just my ramblings

CC

colin563 · « **Reply #16 on:** October 13, 2009, 05:40:07 PM »

the fee rate is as you left it set up slow feed

no coolant or lube is being used

as i said hand feed is great finish but power is different

its got to be down to them brass bushes if not they need changing anyway

thanks colin

NickG · « **Reply #17 on:** October 14, 2009, 06:49:01 AM »

Colin,

I had the same thing on my last lathe, an old Portass. The leadscrew was bent on that so it could be those bushes.

Look at the OD of the flywheel in this pic, it is not that obvious on the photo, but this was after much effort trying to get rid of it! It's hard to describe it's like some sort of rubbing, polishing occurs with that pitch but it's not actual marks from the cutter and feed if you know what I mean, you can see those marks if you look very closely. The actual finish is ok but you got this pattern, am sure it must have been due to bend in leadscrew:

Nick

colin563 · « **Reply #18 on:** October 14, 2009, 08:36:05 AM »

i think the best way to describe the finish

it looks like the finish on a record lp vinyl

and it has a similar feel to it like the record

im just waiting for chester to ring me back on the parts

colin

NickG · « **Reply #19 on:** October 14, 2009, 09:23:17 AM »

what's your tool like, do you need a bigger tip rad?

colin563 · « **Reply #20 on:** October 14, 2009, 09:47:30 AM »

this is the hss tool im using http://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=2&Itemid=17

ive not put a radius on it as its cutting excellent by hand just power feed

i get problems

colin

tumutbound · « **Reply #21 on:** October 14, 2009, 04:52:27 PM »

Colin,
At the risk of getting off topic, how do you find the diamond tool to use?
I've just watched the video and it looks like it will solve most of my tool grinding problems.

colin563 · « **Reply #22 on:** October 14, 2009, 05:51:46 PM »

its a great bit of kit the little bit ive used it

i always finding grinding tools a bit of a pain

the is so easy its foolproof it souns exspensive but i think its worth it

you might find this link a good read
http://www.model-engineer.co.uk/forums/postings.asp?th=29818

also there are a few different design about

and in model engineers worshop #156 you will find a step by step guide on how to make your own

thanks colin

CrewCab · « **Reply #23 on:** October 14, 2009, 07:52:24 PM »

Colin

The last set-up on the lathe was for thread cutting, swap the lead screw cog for for the biggest one available and see if that helps

CC

bogstandard · « **Reply #24 on:** October 15, 2009, 12:07:43 AM »

Colin,

The one area that I didn't do anything with on Darrens lathe, because he had already said he had done something with it, was the leadscrew.

If you can, I would try to get it onto a larger machine and check to see if the end spindles are running true to the thread.

If they are out, there isn't much to play with, but the ends could be turned down and resleeved, then gently turned back to true.

The bearing block at the tailstock end is a real PITA to get adjusted properly, it isn't just a matter of tightening it up.

Remove the tailstock, move the saddle until the leadscrew is just sticking out of the back and use the half nuts to lock the leadscrew in position. Then undo the support block and shim it up and gently tweak it tight until there is no strain on the leadscrew at all.

As already suggested, if you are not screwcutting, the gear train should be set up for the slowest feed possible.

Bogs

colin563 · « **Reply #25 on:** October 15, 2009, 09:58:43 AM »

thanks for the replies again cc & bogs

i will try all of your ideas on this as i dont want to keep removing lead screw

but im just going to get bushes first , just proving a bit difficult to place the order with chester

ive rang 3 times yesterday & today still waiting for them to return my calls

i gave them part # and most of them are at the midlands show

thanks colin

bogstandard · « **Reply #26 on:** October 15, 2009, 11:12:12 AM »

You will be lucky get anyone from any of the suppliers at this time, not until a day or two after the show.

Bogs

colin563 · « **Reply #27 on:** October 15, 2009, 12:04:44 PM »

i just managed to get 1 of the bushes out & its egg shaped

i think the reaso is the ball bearing oiler has had the ball pushed in at sometime

and caused a blockage at sometime in its life

hopefully thats my problem

also got to try & remove whats left of the 2 ball oilers & get replacements for them aswell

colin

bogstandard · « **Reply #28 on:** October 15, 2009, 12:16:03 PM »

http://rdgtools.co.uk/acatalog/Button_Oilers.html

Bogs

colin563 · « **Reply #29 on:** October 15, 2009, 12:24:59 PM »

thanks for that i didnt know rdg sold them

i was looking at arc euro trades site

hoping to pick some bits up sunday at the exhibition

thanks colin

Darren · « **Reply #30 on:** October 15, 2009, 12:53:45 PM »

Colin, I found the headstock end of my leadscrew was machined off center. So I re-machined and made a new PB bearing for the pillar block.

It did indeed help, but not eliminate the problem. I never looked any further because Bogs did some major fixes soon after that.

There is a post somewhere on me machining the leadscrew, but for the life of me I can't find it for you....

colin563 · « **Reply #31 on:** October 15, 2009, 01:37:10 PM »

if you look at the bottom of the picture you can see were its worn

hope you can see it tried couple of ways to take the picture this was the best

i had to drill the caked up dirt out were the oil should be flowing it was packed solid with it

i will check my leadscrew the best i can but i wont be able to machine as only got a about 1ft spare at back of machine

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Author Topic: tried my lathe today (Read 14102 times)

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