Tool Holders

[deeferdog]

The quick change tool holder on my lathe seems to be a bit of an orphan and I have not been able to source a supply for the tool holders at a reasonable cost. The local agent has them for $68 each which is more than I am willing to pay. I had some 2011 aluminium so yesterday I made one and will now test it to see if it is strong enough for the job. The originals are steel with a ground finish. My lathe is small, 250mm swing with a 1 HP motor so I don't suppose the load on the tool holder will be all that great, so here is my question. Does anyone know how to calculate the loads? I imagine that if the holder was loaded to the point of failure it would fracture somewhere around the base of the tool but that's a guess. Deflection would be more with the aluminium holder but would it be enough to affect accuracy? I intend to test this over the next week and if I cannot see any discernible difference I will go ahead and make a further ten. I have posted a few pics, in the first, the original is on the right. Opinions invited, Cheers, Peter

 

[bazmak]

I personally would not be happy with alum,HOWEVER you have done a great job of making it,it should work well but i dont think it will last as long as
a quality steel one.At some point it will start to deform but let us know
Also depends how hard you treat it,light cuts ok but heavy cuts ??
A 10" swing lathe can not be classed as small

 

[Cogsy]

I'd assume it would be strong enough to work by the looks of it, but I'd expect it to flex on heavyish cuts. To test I'd say take the heaviest cut you normally make then take another pass and judge how much more cutting is being done on the 'spring' cut. The holders do look like they'd be tough to make in steel. If you need lots of extra holders it may be better to replace the QCTP with something more common and easier to make holders for in the long run. If you only need a couple it might just be cheaper to pay the $68 (as expensive as that is).

 

[Kerrin Galvin]

Hi Pete,
$68 is a bit step, but I can’t talk as it cost me $40 MORE to have the holder water cut for the knurling tool to Bazmak’s design! Yours look pretty close to a Dickson design. Have you checked out Chronos in the UK? They do a 5 pac at a freely reasonable rate. There’s a guy here in NZ who does single holders cheaper than your quote, given exchange rates .........

Cheers Kerrin

 

[DJP]

After the first few uses check that the cap screws holding the cutter do not become loose. That would be an early sign that the lower portion of aluminium is deforming.

I had a similar decision to make regarding cost of a QCTP. I ended up making custom tool holders for carbide inserts and these were milled to be exactly on centre. About as fast at changing a QCTP holder I can change a tool. It solved my needs inexpensively.

 

[kuhncw]

Peter,

Nice work on the tool holders. That is a complex piece and they look great. This is not scientific, but judging from the look of your cutting tools, you are not going to be doing heavy hogging cuts. It is my opinion your aluminum tool holders will do a fine job on the majority of your work. I took just a quick look at material properties. Your 2011 is a bit stronger than 6061. 7075 would boost yield strength by 50% and give strength a bit above 1018 steel.

Chuck

 

[nautilus29]

Nice job on the holders! If you find you have too much flex maybe you could try to make a holder with a pocket instead of a slot. Kind of like a boring bar holder. Giving the size of your tool you probably won't have to worry about that though. Let us know how it works out.

 

[fishy-steve]

Hi Peter,

I would be nervous of using it for parting off. Having a nasty dig in would be the ultimate test.
I make my own T2 holders out of damaged fork lift truck forks. If you can get some the steel makes for very tough tool holders.
Steve.

 

[packrat]

I do not think $68 is a out of line price for a good holder{I would not buy 10 at that price, if that is what you need}, I would not probable try and make one for that price. That tool holder you made looks real good....

 

[MachineTom]

I was given a BXA in AL, when used on cuts it is NG, you could see it flex. But for holding a thread cutter works fine, and that's all it is used for.

 

[RM-MN]

If you could see the flex of the tool in a BXA toolholder you were making some awfully deep cuts or something was loose. Those are used in industry and work fine.

 

[deeferdog]

Thanks to everyone who has commented on this thread, I now know a lot more about my tool holder. It seems it is a Dickson design and that they were fitted to the Myford lathe and considered one of the best. They have been copied in Asia, and this is apparently what mine is, however Vertex, which is a pretty good Taiwan tool maker, refers to them as the "Italian Style" QCTH as do other Chinese manufacturers. I suppose the Italians copied the Dickson or Dickson copied the Italians, who knows? I don't think the Chinese care. Anyway, nobody is offering the holders much cheaper so I will continue with the testing of the aluminium one. I took 1mm cuts on 20mm1020 steel round bar with fairly heavy feed, certainly the motor had a bit of a moan, this is about as much load as I would put on the machine in the normal course of events. A second spring cut on the same settings produced nothing as opposed to say a boring bar or thread cutter but I'm sure no expert here. I normally don't worry too much about feed rates or depth of cut, I just listen to the machine in the same manner as using a drill press, just watch the chip load and listen to the motor. Not very scientific I know but I've been doing it for a long time and it's too late to change now. I used the holder all day yesterday, the screws stayed tight and the tool remained on centre. It was swapped for other tooling constantly. I would not use this holder for everyday use, I have six steel units for that, however I have various tooling that I would like to lay my hands on quickly but to do that I need tool holders. I intend to go with the suggestion to fashion the holder to the tool rather than a more universal design. If these ten prove acceptable, then I will make further ones as it is cheap and convenient to do so. Finally, I'd like to say how much I appreciate this forum, and thank especially the members who are prepared to contribute their opinions. I am a much better hacker because of you guys. Cheers, Peter

 

[mcostello]

We are all hacks one way or another, sometimes it shows up here in public.:thumbup:

 

[bazmak]

In a lot of posts,common sense prevails with help and advice from others
but at the end of the day if you dont try it you will never know

 

[goldstar31]

Actually, the history is there- but like most things, it will be forgotten.

I have a 'Unimat' or perhaps a clone but a great deal of it is aluminium castings and the old round bar Uni which I once owned-- had even more of the stuff.

As far as Myford was concerned, its other tool holder had an alloy 'boat' but where mine is is not for me at this time having endured 15 courses at a Chinese charity banquet with -- suitable libations. No welding, no machining or even driving today!

However, my hazy recollections recall that it was once 'good practice' to put perhaps zinc or ali sheet under the lathe tool-- which did a lot of things like absorbing the shock of turning on somewhat worn old lathes and today, would go a long, long way to minimise breakages of brittle carbide inserts.

Oh, and little slips of brass sheet to protect work in lathe chucks. What happened to them?

Hic

Norm

 

[deeferdog]

All finished. As you can see from the pics I have ended up with ten similar tool holders. I would have liked to have described them as "ten identical tool holders" but they are not. They are close, and I'm reasonably pleased with them but to achieve the accuracy that I would like, I think that I should have spent more time on the setup or indexed in each piece rather than relying on stops. The aluminium was good to machine but very messy, particularly as some of the cuts were very heavy. I used a face mill rather than a fly cutter and always with a cutting fluid, this stopped any problems with galling on the cutter. The adjusting screws were made from 1020 steel. Total cost was A$43 for the aluminium, steel and the 50 cap screws, better than the $A680 from the dealer. I don't think they are as good as the suppliers but I do think that they will do the job. If any fail in the near future I will post. Cheers, avergoodweekend, Peter.

 

[bruedney]

If you really want some Steel ones and you know someone heading to or from NZ then you can get some from this Trademe seller (NZ Ebay) https://www.trademe.co.nz/business-farming-industry/industrial/manufacturing-metalwork/lathes-accessories/auction-1473115164.htm

Cheers

Bruce

 

[deeferdog]

Thanks Bruce. I hope I don't need them. Cheers, Peter

 

[Blogwitch]

If you are happy with them D, then all decisions should be yours alone. Very nicely done.

If I was attempting that type, I would have a bit more meat under the tool itself, but I suppose, because of the where your toolpost sits, it wouldn't allow the correct height to be set as the holder would hit the topslide (compound) before you could get low enough to get the tip on centre.

Or, you could make the holders as is but to fit the next size down tooling, that would give you a little more underneath support for those heavier cuts.

I am lucky and have a piston type QCTP which allows the holders to sit over the edge of the topslide, so no restrictions on the size of tooling I can use or the support I want.

But again, because you have made them, you have total control and no-one can criticize your work, only make suggestions.

Well done.

John

 

[Cogsy]

They look great and I know there's a lot of work invested in that bundle of tooling. Enjoy!