New lathe arrived today : The ongoing saga

[EmgeeParticipant @emgee]

Hi Brian

Neither listing states the insert tip radius and this radius affects the surface finish achievable, although of course other factors have to be taken into account. The last 2 digits (07-04-02) normally state the tip radius so 02 is .20mm rad and then 04 and 08 are .40 and .80 mm rads.

Ground finish Grade H10, H13 inserts will give the best results on non-ferrous metals and plastics.

Emgee

[Brian JohnParticipant @brianjohn93961]

1. There seem to be quite a number of various shapes and sizes when it comes to replacement tips for indexable tools. Which is the most popular shape/size ie. the most readily available ?

2. I have found a company here in Cairns who will order in a green wheel for touching up carbide tip tools (not indexable tools). What size grit should I order : 60 grit or 100 grit ? The sales person said that the 100 grit is VERY fine and he was not sure if it is suitable. They cost $25 each.

3. I machined an aluminium flywheel today using one of my steel mandrels. Everything went well except for the pits in the flywheel itself ie. casting problems beyond my control. But I did find that my drills and reamers seem to be drilling holes almost spot on 6.00mm ; they do not seem to be oversize at all. If you have to force the mandrel on the flywheel then is the shaft on your mandrel too large ie. Should it go on easily or should there be a slight amount of resistance when fitting the flywheel to the mandrel ?

4. If the axle to your engine was slightly oversize (say 6.05mm) how would you enlarge the hole on your flywheel to accomodate this ?

Edited By Brian John on 02/10/2015 07:40:45

Edited By Brian John on 02/10/2015 07:41:19

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian John on 02/10/2015 07:39:49:

4. If the axle to your engine was slightly oversize (say 6.05mm) how would you enlarge the hole on your flywheel to accomodate this ?

.

Brian,

It's often easier to reduce the size of a shaft to fit a 'good' hole, but; if you need to slightly enlarge the hole then look at techniques like reaming, lapping, honing, boring … [plenty of reading material available]

At that scale, in Aluminium, I would probably make a 'Toolmaker's Reamer'

MichaelG.

[Ian S CParticipant @iansc]

Cowboys, or Broncos.

You can use the green grit wheel to put a new angle on a chipped indexable tip.

Here's the tool makers reamer, does not need hardening for aluminium, file or grind the angle to about 20* (between 15* & 30*). A bit of mild steel will do, if you have excess of the shaft that is to fit the hole use that.

Ian S C

[pgk pgkParticipant @pgkpgk17461]

I'm newish at this too but a 60grit is pretty coarse stuff. The difference between reshaping and resharpening. While I haven;t tried it on carbide (yet) I;d have thought some cheap diamond hones used wet would be a simple way of slicking up a dull brazed carbide..One of those cheapo sets of 120, 240 and 400 grit perhaps. Even f they fail on carbide I can confirm they work well on HSS. And if you shape with a wheel you still need to hone or stone for a food finish.

[HopperParticipant @hopper]

Posted by Ian S C on 02/10/2015 09:53:49:

Cowboys, or Broncos.

It's all Cowboys up here in Cairns mate.

[Chris DentonParticipant @chrisdenton53037]

I've found a bar of hand soap to be good lubricant when using large abrasive discs to cut through 3" aluminium bars.

What the sodium hydroxide in the bar does to the aluminium oxide cutting disc over time I don't know though.

[AjohnwParticipant @ajohnw51620]

Posted by Brian John on 01/10/2015 10:53:53:

I bought an aluminium cutting wheel today ; it is twice as thick as the steel cutting wheels. I am not sure why that is but I will use it next time I have to cut aluminium or brass.

I seem to be using mostly the RH cutting tool since I bought the lathe. I am using the carbide tip tools (not indexable) for roughing cuts and using freshly sharpened HSS tools for taking finishing cuts. This is giving a very good result. Hopper's cutting tools are VERY sharp !

What sort of results should I expect with indexable carbide tips such as these ?

**LINK**

**LINK**

The 2nd link types are fine Brian. I use them but on the 10mm / 3/8" holders. You don't want to buy that set though. Look for ones that come with a torx wrench. The tip fixing screws are far to fine for a modern poorly fitting hex key and the keys round over in no time at all. I would suggest 10mm holders too if they can fit your lathe but from the spec you would need to buy a new tool holder. The one that comes with the lathe seems to be aimed at 5/16in tooling but an odd metric equivalent that comes out at 0.309" +0 -0.012".

The tips on them are old hat though now. You should find a source of tips like these to replace them with at some point.

**LINK**

The triangular tips can be used to work up to and finish shoulders – not so the square ones. The rad on the tip is pretty small so the shoulder can be relived by plunging the tool in a little.

The same style for stainless finishing works well on all materials too but those are coated and the finish does fall off when the coating wears. I intend to try the micro polished aluminium ones on other materials and don't see what they shouldn't work out. Not done yet as I am in a no more work phase until I have completed a very thorough clear out and tidy up. There is some brass work in my photo album done with the stainless ones and no polishing etc. Also the same tip on silver steel showing micro tearing that would polish out very easily. The marks are only a couple of micron deep. It's pretty junky silver steel. The place I bought it off where getting rid of it.

I've found that a 60 grit green wheel is fine for braised tip carbide tools if the tool is moved side to side to finish off. I don't use these much now but did use them a lot. I have green grit on one wheel and a medium grit ordinary wheel on the other for hss and also relieving the tool steel under the brazed tip carbide tools when these were reground.

John

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[Ian S CParticipant @iansc]

I knew it was Brian, I'v got a Niece who lives in Townsville, GOOD LUCK.

Here's a tool holder I made up the other day.  I got a hand full or two of tips at the local second hand shop a few months back for $NZ 2, so I thought I'd try this shape, there are plenty of others too.

Ian S C   PS., it works well, took 2hrs to convert from a high tensile bolt.

Edited By Ian S C on 03/10/2015 12:54:46

Edited By Ian S C on 03/10/2015 12:57:28

[Roger HeadParticipant @rogerhead16992]

Ian S C, that toolholder looks nicely blacked, how was it done? Also, I don't understand "convert from a high tensile bolt". I can see that it appears you are using a normal cap-head bolt for fixing the tip, but what is the 'convert' operation.

I guess the main toolholder body is normal mild steel?

Roger

[Brian JohnParticipant @brianjohn93961]

I have machined that aluminium flywheel by holding it in the hub for the initial operations of facing the hub and drilling out to 6mm. The result was very good. I then used the steel mandrel to hold the flywheel to machine the edges of the rim and the outer main surface. All went well. I will machine some brass flywheels tomorrow.

I have tried touching up the carbide tip tools with a diamond file but it does not seem to help much. I will need to buy a green wheel and a bench grinder.

Edited By Brian John on 04/10/2015 07:43:23

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian John on 04/10/2015 07:27:28:

I have tried touching up the carbide tip tools with a diamond file but it does not seem to help much.

.

Brian,

Just in case there has been some confusion with terminology …

For 'touching up' the edge of carbide tip tools, this is the sort of hone that I use … the red one is a suitable grade.

MichaelG.

[Ian S CParticipant @iansc]

The main tool holder was a (I think) 24 mm 8.8 bolt, I machined it to a square section. I blued it using the gas torch, quenched in water, taken out before completely cool and allowed to dry, then rubbed with oil. The screw is a 4 mm x 6 mm cap screw, to get a proper screw for it would cost more than the tool, and all the tips put together. If I did not have the Allen head screw, I'd either use a slotted/Philips head, or hex, or make my own, we're not fancy here.

Ian S C

[Roger HeadParticipant @rogerhead16992]

Ah, of course… yet another use for all those 24mm HT bolts that we have cluttering up our workshops .

Good one, Ian

[Ian S CParticipant @iansc]

Brian, hope your head's not too sore, congrats' the Cowboys 17 16 in extra time, great for a first win.

Roger, I'v got a whole collection of large salvaged bolts.

Ian S C

[Brian JohnParticipant @brianjohn93961]

Ian : it was almost as though the game was scripted for a movie : equalising try in the last second….. Thurston misses the potentially winning kick when it hits the upright…then redeems himself with a field goal in extra time. It was the first Grand Final win for the Cowboys and this year there was no controversy regarding referee's decisions !

Is cast iron harder to machine than mild steel ?

 

Edited By Brian John on 05/10/2015 11:25:01

[AjohnwParticipant @ajohnw51620]

Cast iron varies Brian so not an easy question to answer. If it happens to be a bad sand casting the skin will destroy hss quickly. I doubt if stuff supplied to model engineers will be that bad. I've mostly used braised tip carbide tools on it. HSS can work out but may need lower cutting speeds than mild steel.

I haven't turned any for a long time so haven't tried indexable tips on it. When making tooling I've used braised tip carbide. At the time these were always supplied in a cast iron grade. They may well still be and have relatively low angles to avoid chipping.

John

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[Brian JohnParticipant @brianjohn93961]

I have been machining a number of brass and aluminium flywheels using my steel mandrels over the last few days and everything was going well until this afternoon when I noticed slop in the cross slide. I have tried to adjust it so that it is even across the full range but I have found that it when it is set correctly at the end closest to me (machining the outer surface of the flywheel) then it is much too tight in the middle (taking a facing cut across the hub)….to the point where it will not move. If I loosen it up here then it becomes sloppy at the end closest to me ie. I can wiggle it around using my hands.

Everything was fine yesterday so what has cause this problem today ? It does not make much sense to me at the moment. Yesterday the cross slide was even across the full range of its movement.

I have given it a good clean and a liberal dose of oil both on the runners and the screw but it is still very stiff around the middle section then loosens up (becomes normal) as it passes this middle part and approaches either of the ends.

 

Edited By Brian John on 06/10/2015 08:28:41

Edited By Brian John on 06/10/2015 08:42:11

[egaParticipant @ega]

Brian John:

I don't know the detailed construction of your cross slide, but with the common parallel gib, slip-stick can be caused by the ends of the adjusting screws riding up the side of the dimple in the gib thus effectively increasing the tightness of the slide; coming back the other way the effect is reversed. The answer is either to dowel the gib to prevent relative movement or to use ball-ended adjusting screws.

[Michael GilliganParticipant @michaelgilligan61133]

Well said, ega.

Geo. H. Thomas described the problem, and its solution very well.

MichaelG.

[AjohnwParticipant @ajohnw51620]

They do wear over time Brian but this seems to be a bit quick. Are you sure that the adjustment screws are in the dimples on the gib strips ?

There is a chance that use will wear machining marks on the slides fairly quickly which is why I usually mention lapping new machines. This is best done with the lead screw out and is described on the Oz Taig site for preparing a machine. Even though the finish on those is good it does improve them. They suggest using some sort of kitchen abrasive/cleaner that is sold in Oz. In the UK I use CIF which is a cream that women reckon doesn't scratch. It's just impossible to tell them that it's slowly wearing surfaces away. The best way to adjust is to do it with the lead screws out as well as it's much easier to judge the amount of drag pushing the slide by hand.

It's often easy to remove the cross slide lead screw on many lathes. They are fastened the same way as your compound slide is. Looks like you would have to remove the handle and slide the whole cross slide off away from the handle and then unscrew the lead screw.

What I do to set them up without removing it is get an idea what the handle feels like when the slide is moving easily. Then position the slide so that the entire length if the gib strip is in contact with the dovetail and tighten all screws firmly. Then back them off and adjust so that they are touching the gib strip and lock them in place and see what that feels like at the handle. There just needs to be a very slight increase in drag from when it was loose. Usually the screws need unlocking and tiny adjustments made but once it's been done a few times it's possible to get an idea just how firmly the screws need to touch the gib strips. I've mostly adjusted used lathes and they generally need several adjustments over time as things settle down. On one lathe there was too much wear to allow them to be set correctly so a compromise has to be used. On my Boxford I accept that the cross slide will be a bit tight when wound fully out. As it's a long slide I could slacken the outermost screw off a touch but I prefer to leave it as is. Some lathes don't benefit much from being adjusted like this but I find smaller ones generally do especially if light cuts have to be taken. Heavier cuts tend to push things firmly home and keep them there. I was stuck on a rather large Lang during training. They had left the slides loose on purpose and the finish was awful and improved dramatically when adjusted, the best I have ever seen. They did this because this is how tool room lathes are often set up. An extreme example. The idea is to reduce lead screw and nut wear and just wear the male dovetail at the corners so that they can then be adjusted correctly if needed. Trouble is that at some point they wont adjust correctly as the whole face of the dovetail develops a taper.

A number of people have found that it is best to buy some slideway oil and use that as well. All I'll add to that is ain't t weird that something that is sold for a specific purpose works better than some alternatives – or is it? I have used motor oil including synthetic etc in the past. I even tried EP gear oil once but the smell put me right off.

John

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[Brian JohnParticipant @brianjohn93961]

Can somebody explain the term ''dowel the gib'' please ?

I am not sure if the adjustment screws are in the dimples on the gib strips. How would I be able to tell ?

Remember, there was no dimple on the sleeve at the tailstock end of the lead screw to keep it in place so it would not surprise me if we had the same problem here ! But I need a bit more information before I start taking the cross slide apart.

[AjohnwParticipant @ajohnw51620]

I'd forget trying to dowel the gibs Brian. Way too easy to mess up. The gib strip should have some dimples in it that the adjustment screws go into. These support it vertically and keep it in place horizontally.

So if you slacken them a touch and move the gib around some how you should be able to feel that the screws are in the dimples. Slacken them more and it might even be possible to push it out. I do have a baby lathe compound slide and there is plenty of clearance taken up with the screws, way more than my boxford.

The tops and bottoms of the gibs are usually angled so that they are horizontal when in place so if you do take it out make sure you put it back in the right way around. They are angled on the compound slide I have and it also has dimples. Sieg I suspect as it came from arc. The lead screw location isn't good enough for what I wanted it for which is why I suggested locking yours when it's not in use.

We all need to boldly go where we have never been before at times Brian. It's not rocket science more a matter of confidence.

John

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Edited By John W1 on 06/10/2015 11:59:36

[julian atkinsParticipant @julianatkins58923]

hi Brian,

i have followed your posts with interest.

my considered opinion is that the lathe you have bought is simply not sufficiently well made or designed to do what you want it to do. having checked the price and converted it to sterling, and looked at your excellent photos of the details of your lathe, i am not surprised.

you can spend hours and weeks taking it apart and putting it back together again but you will never get it to work as you want.

i am sorry to be so pessimistic and unhelpful, but a bit of a reality check is called for IMHO.

cheers,

julian

[egaParticipant @ega]

Michael Gilligan:

GHT rules me from his grave! – a great shame that we don't have the benefit of his views on current developments.

I mentioned ball-ended adjusters but a simpler way of achieving the same effect is to centre drill the end of the screw and interpose a steel ball. And an alternative to dowelling as a way of restraining the gib laterally is to install keeps at each end although this would often be more work than the simple dowel which I agree needs to be done correctly.

[Author]

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