QCTP Question

[jimmyratsbreath]

Hi all,
First I want to say this is a fantastic website.I have learnt a lot already. I have a generic 12x36 chinese lathe.Bought a AXA toolpost from CDCO (another great find from this website.
The t-slot on my cross slide was narrower than the base plate of the tool holder. I tried to machine it but the base plate was hardened. I then lit the bbq and chucked in the base plate and let it cool slowly.this did the trick and the machining went well.
So now do leave the piece unhardened and use the toolpost as is or do I get it hot and quench it before use?

Jim

[pipeclay]

Leave it.

[Dave J]

First off welcome,:2tsup: and as you have probably already seen we have a good bunch of guys here.
As Pipeclay said just leave it, it will be fine. They usually come soft so not sure why yours didn't. The standard piece in my lathe T slot is soft.

What sort of lathe is yours, any pictures? It also sounds like you have a mill.

Dave

[Abratool]

Agree.
Leave it.
regards
Bruce:)

[jimmyratsbreath]

Thanks guys, guess I'll leave it soft then.
Dave J no mill, just figured out how to put on the 4 jaw, centered it and turned away the major diameter and left the minor at full height to shoulder it on the T-slot.
Piece was pretty hard a file wouldnt touch it. Trying to machine it looked like an F1 disc pad at full braking
I wasnt allowed to do metalwork at highschool.Had a bad reputation so when it was time to do metalwork, the teacher marched me off to home-ec saying "here you deal with him" and yet a year later I did jewellery making with him and he was fine.

ps my lathe is the standard green one I see in all the forums, 95 vintage

Jim

[simonl]

Hi all,
First I want to say this is a fantastic website.I have learnt a lot already. I have a generic 12x36 chinese lathe.Bought a AXA toolpost from CDCO (another great find from this website.
The t-slot on my cross slide was narrower than the base plate of the tool holder. I tried to machine it but the base plate was hardened. I then lit the bbq and chucked in the base plate and let it cool slowly.this did the trick and the machining went well.
So now do leave the piece unhardened and use the toolpost as is or do I get it hot and quench it before use?

Jim

Hi there,

Hi Jim, Welcome. There is a lot of experience here on this forum and I have found the guys on here extremely helpful and willing to share their knowledge. This is especially encouraging when, like me you are relatively new and inexperienced in metal working. I have a generic 12x36 chinese lathe too. I would love to hear what you have done with it or improvements you have made.

Cheers,

Simon

[jack620]

Jim & Simon,
are you guys members of the Yahoo 12x36 lathe discussion group?

12x36importlathes : 12x36 IMPORT LATHES (http://finance.groups.yahoo.com/group/12x36importlathes/)

It's for Chinese/Taiwanese 12x36 lathes only. It seems to be very active.

[simonl]

Jim & Simon,
are you guys members of the Yahoo 12x36 lathe discussion group?

12x36importlathes : 12x36 IMPORT LATHES (http://finance.groups.yahoo.com/group/12x36importlathes/)

It's for Chinese/Taiwanese 12x36 lathes only. It seems to be very active.

I'm not actually. I will definitely have a look at that. I was never really into forums all that much as many of the ones I have looked into have not been very friendly or accommodating for inexperienced operators like myself.

Cheers,

Simon

[Darren_111]

Hi Jim,

I bought the same QCTP from CDCO for my Gasweld 12x36 and turned the baseplate down the same as you. I really struggled with that job, it was one of my first. I didn't realise how hard the baseplate was until I got more experience later. At the time I thought all my difficulties were due to the intermittent cut, my noobie ground tools, and my speeds and feeds. Later I realised that the plate was just hard and that conspired with all the other factors :B

I should of asked for help here.... lesson learned!
Darren.

[Pete F]

That's very strange that it was hardened, they are normally sent out soft as they need to be machined down to fit the T-slot.

For others who may read this in the future, there's no need for a 4 jaw to turn a piece like this down, it will fit just as well in a 3 jaw (I mention all this as it's often the only chuck a used lathe comes with), and will simply be turning off centre. Since it's an interrupted cut anyway, and you're simply reducing the width, it won't make one iota of difference.

Pete

[Darren_111]

I understand that it doesn't matter about centering the job to reduce the baseplate thickness, that's a very good point. You can just rotate about any point.

... but what I did (and what I think Jim did) is to leave the centre as shown in the picture. I found it easiest (as a beginner) to use the 3 jaw chuck to clamp the bolt and then screw on the baseplate so it tightened on to the face of the chuck jaws.

If this is a bad method please say.

[Dave J]

Hi Darren,
As you already know it works that way, but it is a lot more rigid if you set it up in the 4 jaw, or even have it on a face plate with a thread rod going through the head stock with a nut and washer at the other end. If you did it this way you would have a bolt on one of the face plate slots to stop it rotating. But the 4 jaw is the easiest if you have one like you do.

On my lathe with my H&F's Dickson style tool post I found I could leave the original stud in and think the stud is a good design the way it locks in their.

How is that new lathe of yours going, we haven't heard anything about it yet.
With your 3 jaw, are they still coming back plate mounted?
If they are, what I did with mine was to machine down the register on the back plate a few thou. This lets you true the chuck up by loosening the bolts on the chuck while you indicate the job in by giving it a bump with a dead blow hammer, then re tightening them. After this you will find it runs true at this diameter for repeated jobs and is pretty good at other diameters.

Also have you found the 2 grub screw for cross slide back lash adjustment? They can be gotten to from the back of the cross slide.
I have still had no problems with mine after nearly 8 years and I have found they wear very little if kept oiled.

Dave

[Pete F]

Darren, I understood the OP was talking about the width of the nut and not the thickness, however maybe I misunderstood that. No there is nothing wrong with what you did, but it will require light cuts and can obviously only be in a direction that causes the nut to tighten. Indeed the advantage in what you have done is the face that is pulled up against the top of the T-slot will now be perfectly perpendicular to the stud, clearly a desirable situation. If you mount it independently in chuck jaws then there is absolutely no guarantee that would be the case and you're instead replying on the stud being accurately drilled and tapped from manufacture. So the end result is, whether you knew it or not at the time, you actually did the job perfectly :D

Pete

[jimmyratsbreath]

Hi guys,
Simon, havent made any improvements yet.The lathe was from a printing plant,bought for $1000.00 with the 3 &4 jaw chucks 2 live centres & drill chuck tail piece tool box change gears,heaps of cutters and boring bars,books etc. Actually went to the auction to buy a mill R-30 clone,which went for $1400 ! thats new price! then this lathe was going to be sold at about $700 before I jumped in.

Pete F I did the same as Darren.However as you stated using the bolt held by the 3 jaw showed a horrendous amount of run-out (tapped out of square) hence the 4 jaw.Like I said earlier she was proper hard,files just slid off.Tempted to reharden and temper just for the experience.I was well chuffed when the hillbilly anealling actually worked.
Dave J my original bolt was thicker, so would have involved a lot more work.This way I can always substitute either depending on the job.
Jim

[Dave J]

Indeed the advantage in what you have done is the face that is pulled up against the top of the T-slot will now be perfectly perpendicular to the stud, clearly a desirable situation. If you mount it independently in chuck jaws then there is absolutely no guarantee that would be the case and you're instead replying on the stud being accurately drilled and tapped from manufacture. So the end result is, whether you knew it or not at the time, you actually did the job perfectly :D

Pete

Mounting it by the stud in a 3 jaw would be (relying) on the hole being accurately drilled and tapped square from the manufacturer.

If you did it in a 4 jaw, you would indicate the face of the plate and indicate the hole by putting the stud in, and then indicating it as close as possible to the plate, which would help cancel any errors if it was drilled and tapped out of square.

It would end up being more accurate than holding it in the 3 jaw if the hole was drilled and tapped out of square from factory as Jim was, and is why he went that way.
Not that it is really needed for this job, but the 3 jaw chucks are not that accurate unless you have a good one, but the contact area on the ends of the chuck jaws is only small for a piece this size to sit on.

Especially with it being a interrupted cut there is also the chance of someone new to machining to take too big of a cut and spin the stud in the chuck, which could damage it.
Sure it can be done in a 3 jaw if the thread is true and you only take small cuts, but a 4 jaw would be clearly desirable in this situation if there is one available.

Hi Jim,
Sorry about that, the reply was directed at Darren as he has the same lathe as me, I will edit it to say so.
It sounds like you got a great deal with that lathe, tooling and books etc. It's amazing how people go stupid on prices at auction like with that mill, but you where lucky with that lathe.
It's also good to here you have a bit of experience in annealing now with this job, and when something else comes along you will know what to do to get it machinable. I still find it strange it came hard as they are meant to be machined to suit the lathe.
It wouldn't hurt to re harden it if you wanted to. You could dunk it in oil to cool it, then have the best of both worlds with it being black and rust resistant.

You bring up a good point about keeping the old stud so you can use either tool post. I was lucky that my standard stud fitted the QC tool post, which I thought was strange as I bought the lathe and tool post from 2 different places. I doubt you will ever change the tool post back unless you need it for a big boring bar or something, but it would make a good rear tool post as a future project.:D

Dave

[Pete F]

Mounting it by the stud in a 3 jaw would be (relying) on the hole being accurately drilled and tapped square from the manufacturer.



Ah, no, indeed as the OP mentioned the stud wasn't drilled or tapped accurately, nor would I expect it to be. By holding the stud you're turning a new face to be perpendicular to the stud.

Yes you could hold the nut in a 4 jaw (if the person has one, many don't when they are initially installing a QCTP) and indicate the stud concentric. That would indeed be a better way in terms of more securely holding the piece. However as I said, light cuts need to be made and there is nothing wrong with doing it using a 3 jaw the way described. Indeed I have held both QCTP nuts and other work by using bolts/studs. You don't press the nut up against the chuck jaws, if you did you wouldn't be able to get to the face that needs to be faced. The bottom of the nut is immaterial, yes you could clean it up if you wish, however it carries no load and may not even be in contact with the bottom of the T-slot.

Pete

[Dave J]

So now where talking about truing the plate to suit crook hole by facing the chuck side of the plate, instead of just reducing it in thickness.
I wouldn't want to do it that way without centre drilling the stud and using a centre in the tailstock to support it. It's not something I would recommend to someone starting out either. Facing it from the tailstock side is delicate enough for a beginner with the interrupted cuts, but facing it from the chuck side with no support could end up with a bent stud with one slip up and it is then buggered and who know what other damage could happen.

If the hole was crook I would just make a new one, but for someone that wanted to use it and since there is no real precision needed for this, using a 4 jaw I would chuck up or collet up the stud up in the tailstock with the plate on the end. I would then bring it up to the chuck and bring each jaw in and tighten them taking care to keep it centre.
The stud could then be taken out and the face machined accurately to the hole.

Most guys mill, file, hacksaw, bandsaw the pieces out and leave it square instead of round. Neither has any real advantage over the other in this situation, though technically the square would be stronger, just different ways of doing it. If you only have a lathe a round one is easier

Dave

[Pete F]

So now where talking about truing the plate to suit crook hole by facing the chuck side of the plate, instead of just reducing it in thickness.
I wouldn't want to do it that way without centre drilling the stud and using a centre in the tailstock to support it. It's not something I would recommend to someone starting out either. Facing it from the tailstock side is delicate enough for a beginner with the interrupted cuts, but facing it from the chuck side with no support could end up with a bent stud with one slip up and it is then buggered and who know what other damage could happen.

If the hole was crook I would just make a new one, but for someone that wanted to use it and since there is no real precision needed for this, using a 4 jaw I would chuck up or collet up the stud up in the tailstock with the plate on the end. I would then bring it up to the chuck and bring each jaw in and tighten them taking care to keep it centre.
The stud could then be taken out and the face machined accurately to the hole.

Most guys mill, file, hacksaw, bandsaw the pieces out and leave it square instead of round. Neither has any real advantage over the other in this situation, though technically the square would be stronger, just different ways of doing it. If you only have a lathe a round one is easier

Dave

No David, I am talking about reducing the thickness, but doing it in such a way that the nut remains perpendicular to the stud. I am not going to argue with you about this, it is a tool post stud being used as an arbour for goodness sakes, not some 3 mm noodle, light cuts are being used and for these it is quite sufficiently rigid, however you are free to machine any way you wish. If you wouldn't do it this way that's fine, and I happen to feel that your suggestion to also use the tailstock for additional support when facing the "wrong" way is a good one and something I forgot to mention. However given that you initially said you thought the OP used a milling machine machine, and from what you've said since, I get the impression you have not done this type of operation before. Indeed now you're talking about it being round, it seems you are not even aware that 3 jaw chucks are perfectly capable of holding both flat and square stock, it's just that they will be turning off centre. Not a problem if all you're doing is reducing a width, meanwhile there is a perfectly good arbour built right in, in the form of a stud. Facing a piece of MS in the normal manner is not at all difficult (or at least it shouldn't be), whether it is being held by a chuck or in this case an arbour.

Many lathes are sold used without 4 jaw chucks. Many people don't have milling machines. These QCTP are from China and so their quality can be a bit variable. This was something I did years ago and now I think more about how it went I recall that the stud on mine was indeed concentric and so I faced the bottom of the nut (definitely the preferred approach if possible). However I am away at the moment so can't check, but if not that nut, I've certainly faced and trued up in similar circumstances. One way or the other, I can assure you I have a rectangular nut under my QCTP that was reduced in both thickness and width and no files nor hacksaws were harmed in the process; it was all done in the 3 jaw and it didn't take long at all. You want to file and hacksaw it instead, then knock yourself out! I have simply suggested to others the way I tackled the problem when I had nothing more than a bare lathe, a 3 jaw chuck, and a crappy American toolpost that didn't even have a "boat".

Pete

[Dave J]

One thing you have to remember on these forums when giving advice, is to think about the safety of someone completely new to the world of machining, as there are a lot of people that read these forums that are not members as well.
We don't want them to end up in hospital or damage their machinery, get disheartened and sell it all before they have even started.
Fair enough a 3 jaw could be used if you don't have a 4 jaw, but it shouldn't be the first choice in this situation if you have a 4 jaw, especially for someone new to using a lathe.



Dave

[Pete F]

One thing you have to remember on these forums when giving advice, is to think about the safety of someone completely new to the world of machining, as there are a lot of people that read these forums that are not members as well.
We don't want them to end up in hospital or damage their machinery, get disheartened and sell it all before they have even started.
Fair enough a 3 jaw could be used if you don't have a 4 jaw, but it shouldn't be the first choice in this situation if you have a 4 jaw, especially for someone new to using a lathe.




In this thread I have simply described how I machined my QCTP. It was not dangerous and there were no hospital admissions in my name. Just because you clearly don't understand how to machine on an arbour doesn't make the technique wrong, heck you may even like to try it some day it's a very handy technique! Sometimes I'm right, often I'm wrong, but all I can do is try to pass on what I've tried and, heaven forbid, learnt. We're all here for pleasure and I'm quite sure others feel the same way too.

Pete

[RETIRED]

Keep it nice Kiddies.:cool:

[RETIRED]

This is renowned as a friendly board where ideas and methods can be discussed freely.

You may not agree with the method but there are ways of putting your point across without slagging off the person that posted it.

If this sniping continues a few bannings may take place.

Play nicely.

[Pete F]

For those who may be going down this path, here are a couple of photos that may help. It's not intended to be a "blow by blow" description of the process, nor a recommendation that this is the correct or only way. Simply how to get the job done if all you own is a 3 jaw, in my experience not uncommon on used machines. As usual, common sense prevails in terms of the depth of cut used and how rigid the holding opportunities are. If I had to do this job again now I would not do it this way as I have a 4 jaw, milling machine, linisher, surface grinder etc etc that are better suited to the task. Most people starting out don't however have any of that, so this is how to get around that situation.

The OP's situation that generated this thread is somewhat unusual from what I've seen. The nuts that are shipped with these Chinese QCTP are deliberately shipped oversize so they can be machined down to the precise size needed for the lathe they're being mounted on. It doesn't matter whether you choose to reduce the width or thickness first, I chose the width. What some apparently don't understand is that a 3 jaw chuck can be used to hold and face other than round stock. Unfortunately I couldn't show this on the nut as I loctited the stud in, but here is a shot of some scrap brass of around the same size. Facing cuts ONLY are used to reduce the width of the nut. To keep the stud centred obviously you only take half the material off one side before reversing the nut and doing the other side. Again, use common sense with the depth of cut, however the nut I had machined easily.

http://i738.photobucket.com/albums/xx21/886014/Lathe/file-7.jpg

The next difficulty is to reduce the thickness (if required). For this I chucked the stud in the 3 jaw and used it as an arbour to once again face ONLY the nut. The poor finish is clearly evident as I was struggling with my old toolpost and poor quality tools. However it got the job done and nobody sees it so it really doesn't matter. As I mentioned above, if the stud is not drilled and tapped squarely then it may be worthwhile taking a light facing cut from the other side just to true it up. As David said above, if you do that it would be a good idea to use a tailstock for additional support as the arbour (stud) will be sticking out a long way. Once the upper face is trued up, push the arbour right back into the chuck and face as per normal.

Here is the finished result. Flat sides, and sized to perfectly slide into the T-slot. No hacksawing or filing is required.

http://i738.photobucket.com/albums/xx21/886014/Lathe/file-6.jpg

Hopefully that helps somebody who is starting out in this area.

Pete

[Stustoys]

If you use the stud as an arbor mounted in a 3 or 4 jaw chuck I believe its pretty unlikely you'll get a face machined perpendicular to the threaded hole. Much more likely that you will end up with a face machined parallel to the bottom of the plate.

As for mounting things in a 3 jaw like that it always makes me way to run. Yes sure its a method that you will see in books and if I really had to I might do it myself. But 1. its putting a side load on 2 of the jaws, 2. The work becomes a huge single toothed cutter(depending on size), 3. It wont come loose it will come out. If the part NEEDED to be parallel or spot on size or square, then maybe. This part doesn't need to be any of those things so for a beginner maybe a hacksaw would be the way to go, depending, it might be faster anyway. Of course they are free to make up there own mind.

Stuart

[Pete F]

Stuart the nut is turning on the stud as an arbour, why do you say it would machine parallel to the bottom of the plate? I can't understand how that is possible. Surely the face will be perpendicular to the rotating stud on which it is mounted?

In what books have you seen this? I was hoping to simply provide a link to this however did quite a search last night and couldn't find one reference. I thought it would save me having to take the toolpost off and take the pictures but alas I couldn't find anything. I've never seen this setup before so I'd be grateful though if you could direct me to the information you've seen.

As far as your points, yes you're quite right, it certainly does put a side load on the jaws and that was something I considered, and indeed looked at again when I took that photo. The chuck I did it on was not the one shown in the photos, it was an old clapped out chuck. Having said that, the jaws run in tight slots in the chuck and are wound almost all the way in so they do get good support. I really don't know what you mean about it being a "toothed cutter", so I'm not sure I can comment on what I found with regard that. Mine machined quite easily with interrupted cuts. Yes if the part had come loose it would come out of the jaws, like I said, common sense is required and the chuck is done up such that the part doesn't come loose! The part is central in the chuck so it's simply rotating about itself and there is no real centrifugal force trying to pull it out of the jaws. A 4 jaw is FAR more secure in this regard as it captures the work, but as I said, if that's not available you can hold work as I showed, it may look somewhat flimsy, but in fact seemed to me to be quite secure. I don't like interrupted cutting if I can avoid it, and these days I'd simply mill it down. But as I said above, mills, 4 jaws and so on may simply not be available.

Regarding the speed, even my bandsaw wouldn't have cut that as fast as machining the part down on the lathe. It was very fast, no more than a few minutes to do each side, so I'd certainly be up for a race with somebody wielding a hacksaw :D Sure if somebody wants to hacksaw it out then they can knock themselves out. I guess the same can be said for machining in general. I am very conscious about putting experiences up here that may be unsafe but I am quite comfortable putting this information up.

Pete

[Stustoys]

Because the nut will pull up against the jaws of the chuck so the faces of the nut will be aligned with them, not the thread.

"The Amateur's Lathe" L.H.Sparey. I'm pretty sure there are others but luckily his was the second book I picked up.

So a beginner needs to find a balance between damaging his chuck and the work piece coming out. That's a pretty steep learning curve. Who knows what his chuck is like. Who knows what speed he will pick. Who knows what his tooling and doc are like. If you look at the leading corner of the "nut" and think about what its doing when rotating you may see what I mean about single toothed cutter. As for centrifugal force, sure there isn't any unless the part starts to slip in the jaws. Once it starts to move off center there will be plenty and nothing to stop it getting worse. Personally I haven't had something throw out of a lathe chuck, but I know someone that has, it missed, but he didn't enjoy the experience. I'm not really sure where "common sense" comes into chuck tightening. Best to avoid where possible, a setup that will throw the work should things not go exactly as planned.

Which is why I said "depending". Depending on how much has to come off. Depending how long it takes you to set it up in the lathe. Depending on how big a cut you are game to take. Depending how fast you are game to run the lathe. A race? sure, my price for loosing is coming second and maybe being a little out of breath, you're price for loosing is coming second and maybe wearing said nut on your face.

Stuart

[Pete F]

Ok, thanks. I would have thought half a poofteen gap would have taken care of the chuck knocking anything off concentric, if that's what was happening, but obviously not. To be honest I now wish I had never brought this up it. I thought it would help other members who weren't fortunate enough to yet have a 4 jaw. My mistake.

[Dave J]

Sorry for the OT, again.
The message has served it's purpose.

Dave

[Pete F]

Dave that's fine. I thought about whether to reply and bump this thread, but decided that indeed I will say a few words here.

I'll be perfectly honest and say that you weren't exactly on the top of my Christmas card list, in fact what you probably didn't know is, for the second time, as a result I'd basically decided to withdraw from the forum and not post any more. Indeed ALL forums unless it was me who was asking for help. I was happy to "take", but I wasn't going to "give" anymore. It was taking a HUGE chunk of my time and I just seemed to be getting crap in return. When I decide not to participate anymore I don't make a big deal and throw a song and dance routine, I just pick up my bat and ball and go play elsewhere. I'm sure many people are very happy when that happens too, though most probably don't even know, never mind care. Unfortunately the above events happened to coincide with some other things that were happening, both in the virtual and my real world and I was simply sick of the number of people who seem to take some form of pleasure in trying to bring others down. It happens everywhere and it's a real shame. Today, after lunch, I'll wheel my bicycle out and go for a ride for a couple of hours, riding in the National Park or on bike lanes, not hurting or inconveniencing anyone, just trying to stay fit and enjoy life. Yet I know that there is about a 50:50 chance (literally) that I will get abused, have bottles thrown at me, get tooted, and so on; I'm not making one iota of difference to their life, yet they're trying to bring mine down. I simply don't understand that thinking. I didn't want to turn on my computer and see the same thing happening on that. I don't think anyone does.

Having said all that, I am no saint. So while I have the floor, if anyone else reads this, it's my turn to say that many MANY times I've read back through my own posts and thought how ugly they read. I can only assure others that there is normally no malice intended, and if there is I will make it quite clear :D Often I'm posting while tired after work (36-48 hours between beds is quite typical), sometimes I use a really lousy choice of words, and sometimes ... well, sometimes I'm just plain cranky! But the intent is generally to help others where I can. You're right Dave, I haven't been at this game long, but in that short space of time I've learnt a lot, an amazing amount when I think back, but I STILL know sweet FA, and as long as I keep that attitude I'm hoping the learning curve will keep at the same steep pace! I try to pass what I've learnt on to others, hopefully I've made the mistakes for them (I tend not to publish them! :D) and I'd hope they'd do the same for me. Sometimes it may sound like it, but I'm not trying to impress anyone, I'm pretty happy with my lot in life and the reality is my feeble machining skills wouldn't impress anyone ... well ok, my 2 year old is impressed when I use the "sparky-sparky machine" (surface grinder, what else would you call it!).

It takes balls to swallow one's pride and make not only a public apology, but also contact a person in private and send the same heartfelt message. So to say I'm impressed is an understatement Dave. Yes I'm sure we'll find plenty to disagree on in the future, but let's hope it's now from a position of a clean slate and mutual respect.

Pete