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Cross slide adjustment

What can happen if the slide is loose

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Ajohnw22/03/2016 17:11:57
3631 forum posts
160 photos

I don't usually bother trying a lathe with a loose cross slide but did for a change. It's a piece of ordinary 1 1/4 dia mild steel.

With a roughing tool lathe as received. Loose as usual.

slideveryloose.jpg

Same tool after the both the cross and compound were set to be a little firm at the handle. Much more even tearing now.

slideadjusted.jpg

Then a quick run over with a micro polished TCGT 11mm indexable tip

slideadjcarbidetool.jpg

surprise No the work hasn't turned in the chuck by the way. It's down to how I put work in it.

4 similar sized cuts.

John

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Edited By Ajohnw on 22/03/2016 17:13:27

Nick_G22/03/2016 19:01:08
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1808 forum posts
744 photos

.

I always now have the cross slide nipped up unless I am using it for a short taper.

Much improved general performance on the lightweight lathes that us hobbyists often use. - Especially noticeable when parting off.

Nick

Mike Crossfield22/03/2016 20:01:39
191 forum posts
17 photos

John

Mighty impressed by the finish in your final photo. Can you give some details about the indexable tip you used? I want one!

Mike

Muzzer22/03/2016 20:26:45
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2904 forum posts
448 photos

Something like this from APT. Usually sold for aluminium cutting but good for fine / finishing cuts in steel too. John's is a large triangular insert but the CCGT06-sized 80 degree insert is used on a lot of popular SCLCR/L tools and boring bars.

Ajohnw22/03/2016 20:42:11
3631 forum posts
160 photos

I just have the compound slide a bit tighter than the cross slide and find I can still get an even feed with it. Some might find it too tight though.

The tips are TCGT 110204 ALU AK10 from apt carbide. They are micro polished rather than coated, Think you will find that they are listed for aluminium and finishing stainless. They do several similar tips but bear in mind the bearings on the lathe do seem to be perfectly adjusted. That can make a big difference all on it's own. The cross slide was tending to move around during a cut initially and the roughing tool I used only has a very tiny tip rad.

I've used these previously which will also give a good finish but find that the coating wears off and hope that the micro polishing extends the life.

finishingtip.jpg

I prefer V nosed tools when they can be used as they will cut both ways, work up to a shoulder and face but the only holders I have found for them is as above in the 10mm 3/8" cheap sets. The ones i have use hex grub screws which are a complete pain compared with torx. APT look like they have some but they turned out to be for 16mm tips.

John

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Ajohnw22/03/2016 22:18:35
3631 forum posts
160 photos

The depth of cut is limited by the design. It's around 1/8" off diameter per cut on mild steel on the 11mm tips. It may well be more than that on very rigid lathes but the length of the raked part which can be seen in the photo of the coated bit will limit it at some point.

There is some brass and silver steel turning done with the coated tip in my album. The sliver steel would only impress if people could run their finger along it. It's glass smooth. The micro polished tips should do just as good a job.

John

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Ajohnw22/03/2016 23:35:45
3631 forum posts
160 photos

teeth While I'm on the subject the idiots that sell indexable tools like these (and others) on ebay don't generally state the tip size or type.

There are 3 sizes. 9, 11 and 16mm. The tool shank size is generally smaller on these particular sets. There is a style of holder that fully exposes the insert at an angle suitable for turning either way and facing, even shoulders lightly. They generally have some number and 92 degrees. The sets sometimes have something similar in them.

They can also be used in boring bars but the RDG ones for instance don't have the tip at an angle where it can face internal shoulders which is pretty stupid really.

The sets of 5 are the best bet in some ways. They often have 2 straight V's as per the photo so one can be used with the tips that come with them that have no depth of cut limit and the other can be used with these rake tipped types.

Don't buy unless they use torx screws as the hex key ones will soon round off the key or any that is used. Actually I have had one of the sockets round after fitting 3 tips so unless I can drill it out it's now useless.

cheeky Some people prefer the romboid come square ones but I much prefer a shape that can easily be used into a corner.

John

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Edited By Ajohnw on 22/03/2016 23:36:49

Mike Crossfield23/03/2016 08:33:13
191 forum posts
17 photos

Thank you for the info. I've always resisted insert tooling except for roughing out cast iron, but maybe it's time to resist my prejudice!

Mike

Douglas Johnston23/03/2016 09:28:06
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611 forum posts
32 photos

I have been a great fan of the micro polished tips for some time, they really do give a superb finish on lighter hobby lathes. They work well on aluminium and steel including stainless.

A seller on ebay under the name "engineering-r-us" sold these tips in various shapes in lots of 50 tips. I watched them for ages hoping the seller would offer smaller quantities that never happened. I then looked to see how much a lot of 50 were fetching and was surprised how cheap they sometimes went for. I then started trying lowish bids and ended up with a few successful bids and 200 tips of three different shapes which will last me forever. Unfortunately this seller has not had any listings for a while so may no longer be selling, but worth keeping an eye out.

If you can't find a suitable holder for any type of tip they are very easy to make and the torx screws can also be found on ebay.

Doug

Mike Crossfield23/03/2016 10:37:06
191 forum posts
17 photos

I've just ordered the ones detailed by John from APT, so watch this space…….

Mike

Ajohnw23/03/2016 10:46:15
3631 forum posts
160 photos

APT offer them in various numbers including 2. However when I ordered one of their holders for the 11mm size they sent one for 16mm so I'm not convinced that their listings are correct. Tip prices are very similar to ebay at the moment.

I've yet to find micropolished parting off blade inserts. I'd like to because one of the main areas where these inserts excel is aluminium. HSS needs a very high polish to match them for lack of sticking etc. They do seem to consume more power than really sharp hss and unlike hss they can't be ground to reduce that ever further via change of angles.

This lathe had another interesting fault that I initially thought was slightly loose bearings causing a little bit of vibration. It turned out to be lack of cleanliness under the compound slide mountings. There doesn't seem to be much scope for this sort of thing or miss adjustment on mini lathes as all of the bits are so thin and light. The tool post was also too far out on the cross slide. it makes more sense to set the compound slide in a position that leaves most of the cross slide guides engaged over the the usual range of sizes and not have it positioned for huge diameters. I set it so that when it was fully in the toolpost could be swung over a reasonable range of angles while still reaching centre.

John

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Lynne23/03/2016 14:14:06
62 forum posts
23 photos

I was interested to see the reference to A.P.T. in recent posts. I chanced to find them as a result of a search for 'Insert stockists' I was quite pleased to find that they made inserts available in packs of two, however, they had no TCMT available which were suitable for general steel turning, they were available but on a minimum order of 10. I emailed them and having identified the inserts I was interested in, they made them available in packs of 2. I was impressed by their approach to customer service and feel that it deserves to be more widely known.

John .I like your idea of one tool to machine R&L. Glanze have a tool, Ref. STECN1010 which pictorially looks identical to the tool you show a picture of, they also show similar tools for R&LH which to me look no different. So I have to assume that there are subtle differences to the inserts.

So the question is:- If I were to replace the tip with a general turning tip (TCMT110204) do I finish up with a tool suitable for R&LH turning. Lynne

Ajohnw23/03/2016 16:16:12
3631 forum posts
160 photos

The tool needs to be angled suitably for maximum performance Lynne. In other words when bar turning in the normal direction the tool should be angled towards the chuck. This is to reduce the effective depth of cut. I don't usually rotate it by 30 degrees so that the cutting edge is square to the work as it would be if a bar turning tool was being used.

I'd say I generally angle it around 1/2 of that and also use it just pointing forwards.

To face a shoulder it needs to be rotated more than 30 degrees towards the shoulder and also when facing the end of the work. The tip rad if I remember correctly is 0.7mm so when a shoulder is faced it can be plunged into the work to remove the radius that would be left avoiding having to fit a grooving tool of some sort most of the time.

The basic shape is a very old idea that was often ground on HSS toolbits but with a more acute V. Usually called a general purpose bit - the one to use for a mix of things. These will even cut both ways even though rake is negative going in one direction. It isn't on the indexed inserts.

The only penalty really is facing - it can be difficult to get the tool edge anywhere near square to the cut when facing the end of work so only a little can be faced off per pass unless the tool is reversed in the holder. They also don't seem to like facing from the centre out. A common trick on larger lathes to get nice shiny ends. Due to the cutting edge angle to work the depth of cut is increased rather a lot so the extra force takes out play in the machine.

laugh Maybe I am biased. I was trained as a toolmaker and while that was going on 99.9% of my turning making all sorts of things was done with this style of tool even though it takes a lot more grinding than the usual bar turning tool.

Looking for another set has proved interesting. There were loads on ebay when I bought the current ones. Not so many now but I did find a decent looking set eventually - Rotagrip and they don't list them on ebay. The set looks expensive but also includes a boring bar that uses the same tip plus 2 torx wrenches. As a company they have been supplying round here in the Midlands for a long long time including when there were a number of very large industrial companies about so it doesn't surprise me that they are fitted with torx even though that sort of user probably wouldn't buy them. As the tip heights are the same on all of the holders they can be swapped easily once the toolpost is set.

John

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Chris Evans 624/03/2016 14:43:20
1478 forum posts

Ajohnw I am in the process of making a new cross slide to dial out the sloppiness on my lathe. New lead screw and nut to be fitted on completion. I really hope I get the sort of results you show.

Ajohnw24/03/2016 15:31:18
3631 forum posts
160 photos

It's mostly down to be able to set the gibs correctly Chris - on all slides that are adjustable but as I mentioned loose headstock bearings will also mess things up but usually if that is reasonable deeper cuts help and fine ones cause poor finish. What deeper means will vary according to the lathe. Faster feed can help too but there isn't much scope for adjustment on mini lathes etc.

Materials vary too and in this case as it's bright drawn mild steel the often hard stringy outside has been removed. Black bar often turns better.

I set the slides via the handle but really it's best to remove the lead screws, oil things up and adjust while pushing about by hand. There should be some definite resistance to movement. Not hard resistance but needing a bit of effort to move the slide. Play in the leadscrew shouldn't really matter then. Some lathes can be adjusted more loosely than others but generally they are always set too loose.

I would suspect that any shape of carbide tip with the same sort of rake design on them would give the same finish. This style is also cropping up on milling cutters now. In this case I like the idea of micropolishing rather than coating as coated inserts do produce a poorer finish when the coating wears off. I'm hoping that they will last longer.

Oh and as mentioned I am accustomed to using V nosed tools.

John

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Edited By Ajohnw on 24/03/2016 15:33:27

Chris Evans 624/03/2016 17:56:16
1478 forum posts

John, my lathe is a 14"x40" Taiwanese job around 20 years old. The slide is starting to crumble around where the compound slide locking screws are (the radial portion) Add to that lead screw wear and no more GIB adjustment left even with 0.020" shim glued to one side of the GIB I am hoping to improve things. I have had a casting made and generally beefed things up and also added thickness to put tee slots in. I will let you know the results when finished. Chris.

Mike Crossfield24/03/2016 18:18:12
191 forum posts
17 photos

Well, I ordered up the micro polished inserts as used by John yesterday, and they arrived today (great service from APT). I set up a 5 inch length of 1 1/2 mild steel (unleaded) round and took a roughing cut to get it running true. Took a couple of 2 thou cuts with a very carefully ground and honed HSS knife tool. 250 rpm/2 thou per rev feed. Finish was what I've come to expect - rather similar to John's second photo. Switched to the micro polished insert and took another 2 thou cut. Very pleased to say the result was excellent. Significantly better than that achieved with the HSS tool. Played around a bit with speed, going up to 400rpm and down to 150 rpm (lathe has VFD) but didn't seem to make much difference. Slight improvement brushing on some neat cutting oil. Doubled the feed to 4 thou/rev. Hard to see a big change. It was quite noticeable that with the HSS tool the swarf came off in long stringy threads, whereas with the insert tool the swarf was in tight curls, and noticeably wider.

Didn't explore different depths of cut since there was so much material extending from the chuck, but I would be interested to know what depth of cut would be ok with these inserts. They are supposedly intended for Aluminium, so I wonder how they would stand up to heavy cuts in steel.

My lathe, by the way, is a carefully set up Myford Super 7. The topside is set slightly stiff, and is normally locked anyway. The cross slide is silky smooth moving - probably a bit too free - but has absolutely no trace of shake.

Mike

Lynne25/03/2016 00:01:18
62 forum posts
23 photos

John, Thanks for the reply, and for the pointers on tool use. I have had a look at the Rotogrip site,

& I think that set TTS5-3 is probably the set you were referring to. Seems quite sensibly priced.

Lynne

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