Should a standard turning tool be mounted at a slight angle?

[JasonBModerator @jasonb]

Posted by Ross Lloyd 1 on 27/06/2018 11:40:10:

I

What's weird though is I bought a 12x12mm index tool holder, not amazingly expensive, about 20 quid from arc eurotrade. Using the supplied carbide tool it immediately had the same problems as the home brew tool did before, even when adding some angle. Makes me think there is something else I am doing wrong.

Can you post a photo of how you have the tool positioned, when cutting right an indexble tool should throw the swarf away from the finished surface so you must have something wrong. Also what material, speeds and feeds would help.

[Ross Lloyd 1Participant @rosslloyd1]

Hi all

Lathe is a Warco WM250V, manufacturer recommends and supplies 12x12mm tools for it.

Material is EN1A Mild Steel. At 40mm diameter I started with the book-recommended 300 rpm, but this produced an awful cut. Increasing to 600 cleaned it up enormously. I have been slowly increasing to 1000+ once down to diameter which for this beginner project, designed to give you a lot of experience of just taking metal off (hence large starting diameter), is 12mm. That was with the original HSS tool, which when reground produced a lovely finish.

Feeds I do not yet have a concept of how to gauge if hand feeding, I am just going with a constant pressure and no "I really don't like this" noises.

Speeds have been the same for the new index tool with cabide, so I need to:

1) Higher speeds if using the Carbide

2) Locking the cross slide no matter what the tool

I will try to get some shots of the tool mounting next time I get to turning.

Cheers

[Ross Lloyd 1Participant @rosslloyd1]

Posted by Mick B1 on 27/06/2018 12:48:30:

Posted by Ross Lloyd 1 on 27/06/2018 11:40:10:

…

Am going to experiment with locking the cross slide, as it does seem super sensitive, as well as getting the tool overhang as small as possible.

Cheers

Yep, first thing to check. Lock all the slides except the one delivering the cut. If you get an improvement, check and adjust the gibs over as full a range of movement as you can.

Hi Mick

Thanks for the reply! Can you explain what you mean by checking it over a full range of movement? The cross slide just has a single allen bolt that you tighten. Should I expect it to have more play at different points along its length?

Cheers!

[Ross Lloyd 1Participant @rosslloyd1]

Posted by JasonB on 27/06/2018 14:31:17:

Posted by Ross Lloyd 1 on 27/06/2018 11:40:10:

I

What's weird though is I bought a 12x12mm index tool holder, not amazingly expensive, about 20 quid from arc eurotrade. Using the supplied carbide tool it immediately had the same problems as the home brew tool did before, even when adding some angle. Makes me think there is something else I am doing wrong.

Can you post a photo of how you have the tool positioned, when cutting right an indexble tool should throw the swarf away from the finished surface so you must have something wrong. Also what material, speeds and feeds would help.

Hi Jason

It is throwing it away, but it feels like from time to time some of the chips get caught or go under the tool, which results in the swarf rubbing on the face. You can feel a clear grinding sensation through the handwheels. Is it possible this is just because I do not have the cross slide locked? This only happens with the index tool, which has a much smaller nose radius than my ground tool. The latter cuts really nicely now.

Will try to get some shots too.

[Neil LickfoldParticipant @neillickfold44316]

Loose compound slides, and loose or improperly adjusted cross slides, all add to poor surface finish. I only use the low speed range of the motor to the clutch, so max is like 700 rpm or so. The ground inserts for Al etc work really well like a hss tool. I find that using very sharp tools is the key to a good surface finish, as well as slide etc in very good order.

Neil L

[Mick B1Participant @mickb1]

Posted by Ross Lloyd 1 on 27/06/2018 17:32:05:

Posted by Mick B1 on 27/06/2018 12:48:30:

Posted by Ross Lloyd 1 on 27/06/2018 11:40:10:

…

Am going to experiment with locking the cross slide, as it does seem super sensitive, as well as getting the tool overhang as small as possible.

Cheers

Yep, first thing to check. Lock all the slides except the one delivering the cut. If you get an improvement, check and adjust the gibs over as full a range of movement as you can.

Hi Mick

Thanks for the reply! Can you explain what you mean by checking it over a full range of movement? The cross slide just has a single allen bolt that you tighten. Should I expect it to have more play at different points along its length?

Cheers!

There are usually 3 – 5 adjustment screws with locknuts along one side of the crossslide. You screw these in to just snug the gib strip against the dovetail with minimal friction. But if the crossslide has significant wear, this won't be evenly distributed over its length, and you'll often find that a setting that's right for one place will be loose or binding at another. Then the game becomes one of compromise, to fond a setting that works across the full travel. You have to remember to balance all the adjustment screws. You're likely to end up with one or more loose spots, and if you can't avoid working in those ranges of travel you may have to lock your crossslide when doing so.

The single Allen bolt is almost certainly the locking screw.

You only really need to check the gib adjustment screws if tightening the locking screw gets a distinct improvement – or if you can detect play be rocking the slide.

If locking the crossslide gives no improvement, there could be a similar issue with the compound slide gibs.

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