How to adjust?

[jeephaydon]

Hello everyone,
I don't know if i've got this in the right place but i'm new to the forum. I've got this lathe which i think is a Harrison l5 11". The problem is that there seams to be a lot of slop in the cross feed you can more the handwheel about 0.4mm on the dial before the tool post moves and the small slide wheel is the same but less. And if you grab the toolpost and move it you can feel that theres play there. Apart from that it's fine but i find it hard to make anything to a presise size. I don't even know if it can be adjusted thanks in advance if anyone can help.    

[stevec]

jeep, hello and welcome. I don't know what  0.4 mm means, is the dial metric? About how many degrees of rotation would that be?
It seems like it could be normal and not excessive wear.

Steve

[DaveH]

Steve, I think he is talking about 'backlash' so he dials in .016" (.4mm) before the cross slide moves.
A little on the much side, normally it can be adjusted, Mick has a similar lathe he may know how it is best adjusted.
 
DaveH

[jeephaydon]

Yes Steve it's metric ,and it is backlash what i'm talking about but i couldn't think of the word i'm pretty poor at explaining things. But if i make a pass on a bit of material and then go back it takes more metal off you can go back and forth probaly 3or4 times without moving the cross feed and it will still take material off. I don't have much experiance but it just doesn't seam right.

[stevec]

(02-18-2015, 08:00 PM)jeephaydon Wrote: Yes Steve it's metric ,and it is backlash what i'm talking about but i couldn't think of the word i'm pretty poor at explaining things. But if i make a pass on a bit of material and then go back it takes more metal off you can go back and forth probaly 3or4 times without moving the cross feed and it will still take material off. I don't have much experiance but it just doesn't seam right.

Jeep, If understand you, you mean you take a cut and the retract the carriage for a second cut and without advancing the tool the second pass removes more metal, even several times?
Do you back up the tool to reverse the carriage? I|f not, does it cut material as you retract for your second pass?
If so I'd say you tool geometry/sharpness/ center height may be off.

Steve

[jeephaydon]

I'm not moving the whole carriage, just the smaller top slide, because the carrige wheel is so high geared. And no i don't back the tool out. The centre hight and everything is okay.
- Haydon

[stevec]

(02-19-2015, 07:07 AM)jeephaydon Wrote: I'm not moving the whole carriage, just the smaller top slide, because the carrige wheel is so high geared. And no i don't back the tool out. The centre hight and everything is okay.
- Haydon

Haydon, I would then guess that you have play in the cross slide and/or the compound slide. Have you tried adjusting the gibs?

Steve

[Sunset Machine]

Backlash is mostly just something to be aware of, it doesn't really affect anything. At least not anything I can think of at the moment. My lathe has a full turn of backlash in the cross slide. About shot, but it can produce work within a few tenths (.003mm).

What you are describing sounds more like spring in the tooling to me. Perfectly normal. Get used to making two or three "spring" passes and you'll be fine.

on edit: I just thought of one thing about backlash- it's annoying! Threading requires pulling out the tool bit for the return trip. Shouldn't have to turn the handle much, but I have to unwind mine a full turn before it starts to move. So it's a time wasting annoyance.

[DaveH]

Haydon,
Sunset is correct, it doesn't have a great effect ........... provided everything else is correct and 'tight'.

I'm sure Mick (Micktoon) will be along shortly to give some help in the matter. He totally rebuilt his Harrison lathe so he should know something about it  

 
DaveH

[EdK]

Excessive backlash could be a symptom of some other problem though.

Ed