New lathe arrived today : The ongoing saga

[Ketan SwaliParticipant @ketanswali79440]

Posted by JasonB on 16/11/2015 13:21:18:

I would think it has a larger minimum bore, say the cutting edge is at 7mm from the bottom of the tool then that is going to be a minimum of a 14mm hole depending on how much of the end is ground to give clearance below the cutting edge.

Ketans little set of 4mm bars work quite well in tight spaces

For the 8mm HSS one in Brians set, you are right Jason. After checking, it is likely to be 16.x mm+ hole needed to use the one in Brians HSS set, unless he grinds it in some way. So sorry and thank you for the correction

Ketan at ARC.

[Neil WyattModerator @neilwyatt]

This is the underside of an HSS boring bar from a set like Ketan's – ground so that it can be used in a smaller hole.

Only ground at the tip and used at an angle because I wanted to do a shallow blind hole and not weaken the tool, but you could grind further along the length of it

[Ian S CParticipant @iansc]

I started to make a new boring bar this afternoon, it will be about 2" long, and the body of it 1/4" dia, the brazed on tip is a tip from an old circular saw. I have a smaller one some where, but the workshop gnome has borrowed it, hope it comes back. These tips are ground left and right, and come in a number of sizes. Available free from wrecked saw blades.

Ian S C

[Gordon WParticipant @gordonw]

To help with sizing a boring bar, and to envisage what is happening when you grind them, I find holding a washer up against the cutting end is useful. Or just drill a hole in a bit of plate. This way you can see how the clearance varies with tool hight and angle etc.

[Brian JohnParticipant @brianjohn93961]

How hot should the lathe chuck get ? I have noticed that the chuck is getting quite warm/hot to touch these last few days. Yes, it is very warm here now in Cairns but I am not sure that is the reason. I am only turning small aluminium parts at the moment.

[JasonBModerator @jasonb]

You should not get any heat in the chuck making those small pats. Is the head also getting hot where the spindle exits? Could be the bearings are a bit tight.

J

[Brian JohnParticipant @brianjohn93961]

Yes, the whole thing feels quite warm.

[AjohnwParticipant @ajohnw51620]

Bearings are supposed to run a bit hot Jason. Perhaps Brian can feel how hot under the rear bearing with a finger in the spindle bore. If it's ouch hot something is likely to be wrong. Very warm should be ok but it this is a bit subjective and just my opinion. It works for me. I also check at max speed, They will be even warmer then.

I'd guess that a major source of heat is the motor especially if Brian is running it for significant periods. That all by itself could warm the entire lathe up. It wouldn't surprise me if the motor was too hot to touch or HOT after say 10 to 15min running. That is around the same period needed to get the bearings as hot as they are likely to get.

John

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[Brian JohnParticipant @brianjohn93961]

I did not notice it ever running hot before but the weather has turned extremely hot lately so perhaps this is to be expected.

There do not seem to be any lubrication points for the spindle or the bearings ? Is this normal for a lathe ?

The instructions say  :  ''the work spindle bearing is pre lubricated and it is not necessary to lubricate it again.''

Edited By Brian John on 04/12/2015 10:17:12

[AjohnwParticipant @ajohnw51620]

Many bearings are sealed for life Brian. There isn't a clear definition of what life is other than at some point they become unfit for purpose.

The other problem with lathe bearings in particular is that as supplied on a new lathe they don't have much grease in them at all. If more is added it leads to more friction and more heat. They all tend to gloss over that aspect even if the lathe has grease points for the spindle bearings. Instructions vary. Wabeco for instance say lubricate the lot every 8 working hours even the spindle bearings and every 500hrs check bearing heat giving no idea what it should be. Ok if some one has a new lathe as they can feel it and get some idea how hot they should be. I'd assume this is taking account of that the lathe may have done a lot of high speed running. 2,500 rpm is pretty fast for a 3 morse spindle. Traditionally it would be 1500 rpm max. Even slower earlier on.

I need to go out but when I get back and I'll look and see if it's possible to pop a bit of grease in now and again, or maybe some one else will.

John

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[JasonBModerator @jasonb]

With the belt off just check that the spindle turns freely.

The were some Far eastern lathes that had a tendancy to get hot and that damaged the bearings, had it on mine but now I have fitted FAG ones runs as cool as a cucumber

[AjohnwParticipant @ajohnw51620]

The lathe uses 6003-2Z bearings so sealed both sides and in any case as there is a plate that is part of the spindle on the front it's doubtful if any grease could be pushed in. The same plate may make it difficult to get the front bearing off. Sounds like Jason may have an answer to that as I believe his lathe has the same sort of chuck mounting arrangement.

I think Opti do state some where that they use hardened bearings but ………………………..

Boxford seem to have a bearing heater just to make sure that the front bearing is difficult to get off. Worse still it seems that they use it on the rear one too so adjustments need a drift and a hammer unless some one has been in their before.

John

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[Brian JohnParticipant @brianjohn93961]

My new larger drill chuck arrived today : 3-16mm B16 taper. This is needed to hold the tailstock die holder the shank of which is too large at 12.7mm for my smaller 1-10mm drill chuck. The MT1/B16 arbor also arrived (from a different company). Is it seated properly ? There is still about 5mm not inside the drill chuck…I thought it would go all the way in ?

NOTE : I have to cut down the arbor so it fits in my tailstock which is MT1 short.

Edited By Brian John on 28/01/2016 08:04:42

Edited By Brian John on 28/01/2016 08:05:10

[Russell EberhardtParticipant @russelleberhardt48058]

That's a strange looking die holder Brian. It looks as if it would have to pull the tailstock along in use.

Usually the holder slides on a parallel rod and is prevented from rotating by a short handle. A simple project to make yourself to fit your lathe.

Something like this: **LINK**

Russell

[Ian S CParticipant @iansc]

I got two different sizes of those holders at the clearing sale of a tool store in Christchurch (NZ).

Ian S C

[AjohnwParticipant @ajohnw51620]

I would expect most of the taper to fit into the back of the chuck Brian. Maybe around 1mm proud.

You can check the B16 sizes from a link on this page

**LINK**

You could turn the die holder you have into a sliding one by turning the end of a drill chuck arbour parallel to suit the hole in the die holder. Your carbide tools should be ok on the B16 arbour. You may need a 2mt to 1mt sleeve to hold the work in the head stock spindle. I can't remember you headstock taper.

To be honest when I needed 1mt arbours I parted off and turned down used 1mt reamers on a Hobbymat. Screw cutting them if needed was ok too but the dog clutch needed deburing with a file afterwards. That is what started me off converting brazed tip parting off tool into screw cutting tools. In this case it's probably possible to get a reamer running true in the 4 jaw.

John

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Edited By Ajohnw on 28/01/2016 18:15:42

[Brian JohnParticipant @brianjohn93961]

Thank for the link John : correct size at big end is 15.733mm whereas mine is 15.90mm so no wonder it is sticking out a bit. It was a cheap arbor from China so I guess we shouldn't expect too much ! I cut it down to size today so that it will fit in my tailstock chuck. It all seems to work quite well. I can now hold my large 12mm stub drills which saves using the boring bar when boring out a cylinder ; I just use the boring bar for the final cut and finish.

[Brian JohnParticipant @brianjohn93961]

I have a problem with the tailstock. I was cutting an M3 thread on some silver steel using the lathe to keep things square ie. work piece in the chuck and the tailstock barrel pressing against the die. All of a sudden the tailstock seized up and would not turn in or out. I have used this method to cut threads many times and this has not happened before. I expected to find some swarf in the tailstock somewhere but that was not the cause.

I pulled the whole tailstock assembly apart to examine the problem : the barrel/pinole (part 402) and the bushing (part 408) had suddenly become to large for the tailstock ! Even with all the grub screws taken out, these parts could not be removed or reinserted by hand ; I had to knock them out with a hammer and punch. How can this happen ? I removed the barrel and polished it up with 1500 grit and that seemed to work okay as it is now a good fit. But I have taken too much off the bushing (I should not have used a file) and the whole tailstock is now wobbly. It is good for nothing in its present state.

I have called Machinery House and they do not keep such parts in stock. They suggested I make one up myself which I will have to do. I do not think this lathe is very good with large steel parts. Could the bushing be made of brass ? I am hoping that a new bushing will solve the problem otherwise I am all out of ideas. I buggerised around with this all afternoon. I still do not know why it suddenly stopped working ; it was fine yesterday.

Edited By Brian John on 18/02/2016 06:24:54

[HopperParticipant @hopper]

Brian that seems very odd. Have you checked for swarf in the moving parts and burrs on the barrel / Pinole (WTH is a pinole anyway?) along the groove where the grubscrew 404 locate?

Is the pinch bolt 4054 backed off? ISTR it had to be set just right for things to work smoothly. Too loose and the barrel flops about the place. Too tight and the barrel will not move. Needs to be set so there is just a bit of drag perceptible.

It's hard to see how a loose fitting bushing 408 would make the whole tailstock floppy. The barrel should be guided by its fit in the hole in the casting, regardles of whether the bushing is even in place or not. And when installed, the grubscrew should hold the bushing in one place and not allow any slopping about.

If that bushing is designed to rotate with the spindle, I would make the new one out of steel so the grub screw does not wear it quicklly. But if the bushing stays still and the shaft rotates inside it, brass might be better.

[JasonBModerator @jasonb]

Have you been oiling the barrel?

Could your 40deg heat have cause the parts to expand.

[Brian JohnParticipant @brianjohn93961]

Hopper : I will have a closer look at how everything works tomorrow as I have to go to work tonight. ''Pinole'' is the term used in the manual ; ''barrel'' seems to be the common term for it. I had backed off all the bolts and grub screws (404 and 405) but everything was so stiff that the barrel had to be removed with a punch and a hammer !

Jason : surely 40 deg heat would not cause metal to expand that much unless it was directly exposed to the sun ? There was plenty of oil in the barrel once I had removed it ; it was not dry.

Edited By Brian John on 18/02/2016 07:35:42

[JasonBModerator @jasonb]

Looks like the barrel has been rotating probably due to the grub screw nearest the headstock comming loose and not seating in teh keyway.

If you click the photo sof 31st Jan you cannot see the scale printed on teh barrel, latest photo you can see the scale.

If the barrel rotated against the grub screw it would have made it tight, the bush is probably meant to be tight as that is what the screw acts against and it takes the thrust.

[Brian JohnParticipant @brianjohn93961]

The scale has always uppermost ; it is sometimes not visible due to the angle of the light or if the flash is used.  If you enlarge that photo of the 31st and look closely you will see that the scale is on the top. The barrel has not been rotating.

Edited By Brian John on 18/02/2016 08:34:04

[Ian S CParticipant @iansc]

Brian, there is a possibility that the barrel may rotate slightly against the grub screw in the keyway underneath, and raised a very slight burr. The problem I had with my tailstock was when I had it too far out (on about the last thread), when I was drilling a deep hole, and the thread burred over, just as it got to the end, and it would not go back in. No fault of the lathe, the book says 95 mm travel, but 85 mm is the usable travel (on my lathe).

Ian S C

[AjohnwParticipant @ajohnw51620]

Sounds like the thread was binding or however the backlash is set up had worked itself too tight. Unless of course the barrel was extremely tight when the screw and etc was removed but I wouldn't expect that to be very loose. i doubt if I could push the one out of my lathe easily by hand as I can feel stiffness via capstan arms about 150mm long which gives a fair amount of mechanic advantage via the rack and pinion it drives.

Sometime Brian I suspect you need to think more before jumping in and figure out how this works before doing anything to it.

I reckon brass should  be ok with some grease but may not last as long as steel.

John

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Edited By Ajohnw on 18/02/2016 13:02:15

Edited By Ajohnw on 18/02/2016 13:10:48

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