Opinions on Quick Change Tool Posts.....

[ddoyle]

I was just wondering what everyones opinion on which QCTP was better built and all... I bought my first lathe about 3 weeks ago, although some have said it is a "toy" since it is a Harbor Freight 7x10 Mini Lathe.  I bought it for a hobby as I have never machined before.  I have surprisingly done fairly well with it, actually had my first successful part-off tonight, and by successful I mean, the part I was cutting off hit the bed of my lathe before part of my parting tool!!! .  Anyway, when I bought the lathe, in my haste I went ahead and got the Harbor Freight QCTP, and although it does what I need for the most part, it just doesn't seem to be as well made as some I've seen on the internet since my purchase.  I can't put a 1/2" parting tool in my tool holder, it bottoms out about 3/16" or so above center, although Chuck in E. TN kinda fixed that for me lol...he milled just a touch off of the end of my cross slide so my tool post was barely past the end, allowing my tool holder to drop past the top of the cross slide, but this seems to make it less sturdy.  So I was just wondering if I decided to invest in a "better" QCTP for this lathe, what would you guys suggest.  Thanks in advance!!

[BaronJ]

Hi there,

I've been through this  conundrum a couple of times.  Having had a good look at what was around, both commercial and home brew, I decided to go down the home brew path.  I have a Myford lathe so I needed something of a suitable size.  I was given a copy of the plans for this one, which is quite straight forward to make and if you wished you could modify the dovetail dimensions slightly to use commercial tool holders.

Modify the drawing to suit your lathe.

[Arbalist]

Do you need a QCTP or do you just want one? I use the standard four way tool post that came with my lathe and it works fine. I've stuck shims to the bottom of my insert toolholders so they're always on centre. Tightening two or three bolts only takes a few seconds ...

[PekkaNF]

I have seen a plenty of parting off tool holders on hobby size and pretty much all of them need some serious work.

I have had four lathes, but I'm hobbyist no way professional - following is just opinion based on my take on lathes between 60 to 960 kg weight lathes.

Biggest problem is that parting off is hard enough and I don't want any extra overhang on parting off blade, not forward and not sideways. QC toolholder easily places the cutting blade wrong side of the cross slide way or least hangs it outside of footing. Look at your setup and check where the blade is in relation of the cross slide - it should not hang outside of the guide ways. I removed the top slide and made an sandwich insert to replace the top slide. Lost some of the versatility, but gained a lot of rigidity. Hardest part was to decide where to the mounting bolt, it needed a lot of consideration and compromise. I tried out normal internal and outside turing tools and also parting off. Ended up threading two holes, one for general outside turning and one for boring operations.

QC-toolhoder should allow height adjustment, but sometimes there is not enough headroom. I fitted 20 mm high insert parting off tool shank on 3/4" size QC-holder, but I milled off some mm of QC-holder. Still considering making a special integrated QC-toolhoder that has minimum sideways overhang for insert paring off tool blade.

Pekka

[ddoyle]

Hi there,

I've been through this  conundrum a couple of times.  Having had a good look at what was around, both commercial and home brew, I decided to go down the home brew path.  I have a Myford lathe so I needed something of a suitable size.  I was given a copy of the plans for this one, which is quite straight forward to make and if you wished you could modify the dovetail dimensions slightly to use commercial tool holders.

Modify the drawing to suit your lathe.

Thanks for the info and pics Baron.  I may try to figure out a design for my specific lathe that will work better for me and see if ol Chuck in E TN is up to some milling, drilling and slicing .

Do you need a QCTP or do you just want one? I use the standard four way tool post that came with my lathe and it works fine. I've stuck shims to the bottom of my insert toolholders so they're always on centre. Tightening two or three bolts only takes a few seconds ...

I don't "need" a QCTP, but I definately like the ease of setting a tool on center, locking it down, and then being able to remove and drop back in and take off.  I've tried the shims before my QCTP got here, and I never seem to be able to hit it just right, touch high or touch low.  I guess I could find more of a variety of shims and that would work.

I have seen a plenty of parting off tool holders on hobby size and pretty much all of them need some serious work.

I have had four lathes, but I'm hobbyist no way professional - following is just opinion based on my take on lathes between 60 to 960 kg weight lathes.

Biggest problem is that parting off is hard enough and I don't want any extra overhang on parting off blade, not forward and not sideways. QC toolholder easily places the cutting blade wrong side of the cross slide way or least hangs it outside of footing. Look at your setup and check where the blade is in relation of the cross slide - it should not hang outside of the guide ways. I removed the top slide and made an sandwich insert to replace the top slide. Lost some of the versatility, but gained a lot of rigidity. Hardest part was to decide where to the mounting bolt, it needed a lot of consideration and compromise. I tried out normal internal and outside turing tools and also parting off. Ended up threading two holes, one for general outside turning and one for boring operations.

QC-toolhoder should allow height adjustment, but sometimes there is not enough headroom. I fitted 20 mm high insert parting off tool shank on 3/4" size QC-holder, but I milled off some mm of QC-holder. Still considering making a special integrated QC-toolhoder that has minimum sideways overhang for insert paring off tool blade.

Pekka

Pekka, nothing has stumped me more with machining than parting...I broke 7 parting tools trying to to part a single 1 1/2" diameter part I had turned and bored, Only had about 1/2" to cut through to reach the bore .  I've been practicing on aluminum lately but still when I'm parting I'm waiting  on the snap of the blade .

Thanks for the replies guys...

[Arbalist]

QC-toolholder should allow height adjustment, but sometimes there is not enough headroom.

Pekka

That's a good point. There was plenty of adjustment on the Dickson toolholders we used on the M300 Harrison's at work but may be a problem on little Lathes.

I guess I was lucky with my HSS parting Toolholder, again it just goes straight into my four way and is bang on centre height.

The insert parting tool I bought was way off though so I had to make a new block. This again just goes straight in and is on centre, no adjustment needed.

[vtsteam]

Here's how I made mine, they work with both my Craftsman 12" and my homemade Gingery lathe. You just need to have a post the same size that bolts to a lathe carriage. I'm even thinking of making a post for the milling machine -- since I recently turned and faced a homemade flycutter to make it true with the R8 spindle on that machine.

http://madmodder.net/index.php/topic,8415.0.html

[bp]

I'm with vtsteam.  I have a Sieg C3, like your 7 x 10, only 7 x 13ish.  I used a 35mm diameter post, to keep things as stiff as possible, bought the 50mm x 50mm free machining bar as 25 mm slices off the square bar.  Then spent a fair bit of time making all the toolholders, I'm now up to about 20.
The 35mm bore in each toolholder was done carefully to minimise the amount of deflection when clamping, this increases the area in contact between the post and toolholder.  Which in turn makes the whole set up stiffer.  Two clamping screws were used to make sure, on reflection they could probably have used only one.
The main aim of all this was to reduce chatter and make parting off easier.  Chatter has certainly been reduced considerably, and parting off is now a piece of cake.  This morning I was parting off 20mm diameter cast iron at 200rpm, al. alloy is regularly parted off at up to 700rpm depending on diameter.  The big advantage of a 7 x ?? machine is that paring off can be done with the spindle running backwards, with the p/o tool upside down.
cheers
Bill

[vtsteam]

Hey that two piece parting tool holder is neat!! 

[PekkaNF]

Not the traditional industrial design, but the parting off blade comes as close the center of tool post as possible. Very good.

Here is pretty standard case, you can see parting off tool hanging outside of cross slide:
http://www.mini-lathe.com/Mini_lathe/Reviews/a2z_qctp/pt03.jpg

You wonder why he rather uses band saw?

I have seen sometimes parting off blade on offset mount:
http://littlemachineshop.com/Products/Images/480/480.1701.jpg

Which is hung on standard QC tool holder.
Which is mounted on top slide, that is allready very close to leftmost part of the cross slide....therefore bit too much overhang and a lot of speculation why paring off is so much easier on centrally mounted rear tool holder - which ever way.

Pekka

[RodW]

Here are some random thoughts.

Re shimming tools, beer can cut into strips is great for fine adjustment (best to empty the can before cutting up) . Hacksaw or bandsaw blades make handy shims too.

As far as parting goes, I fixed my problems  after I upgraded my lathe (13"),  bought a BXA QCTP and added an insert parting tool and matching holder although a HSS tool in the standard BXA holder worked well. A powered cross slide is also handy for parting now!

From my past expereince, I think the smaller lathes don't have the power and rigidity to  part off easilly. Now it is a breeze!

[Bigbadbugga]

 
I use an old set of feeler gauges as shims on the boxford.

[Arbalist]

Metal strapping used on crates is good for packing as well.

[BaronJ]

Metal strapping used on crates is good for packing as well.

Hey don't forget the plastic stuff !  Not only good for packings but great for anti marking, particularly in the four jaw.  If yours is anything like mine the jaws have lots of sharp edges that cut into your work.  I also use a hole punch and make little discs out of them to put down the hole under grub screws to stop them marking when you tighten them up.

[bp]

The way that I look at is this.  Getting the tool accurately on centre is important, especially with small machines.  I got fed up and disillusioned with shuffling bits of metal as shims, 50 years ago, during my apprenticeship.  Nowadays, with the availability of  adjuster screws on my toolholders and using a centring scope in the tailstock, setting up a new or sharpened tool takes about 30 seconds.  It's spot on, and set until it's next sharpening.
I got the centring scope when it was on sale at Enco, mainly for use in the mill.  It has other uses!!  If you don't have a scope, there are dozens of tool height setting gauges.
A QCTP gives you more than a quick change tool post, shim shuffling is very last century.
cheers
Bill

[ddoyle]

The way that I look at is this.  Getting the tool accurately on centre is important, especially with small machines.  I got fed up and disillusioned with shuffling bits of metal as shims, 50 years ago, during my apprenticeship.  Nowadays, with the availability of  adjuster screws on my toolholders and using a centring scope in the tailstock, setting up a new or sharpened tool takes about 30 seconds.  It's spot on, and set until it's next sharpening.
I got the centring scope when it was on sale at Enco, mainly for use in the mill.  It has other uses!!  If you don't have a scope, there are dozens of tool height setting gauges.
A QCTP gives you more than a quick change tool post, shim shuffling is very last century.
cheers
Bill

Bill, I agree about the shims....I tried it for a few days after I got my lathe, while waiting on my QCTP to get here.  As I had never even turned a lathe on before, I bought a 7x10 from Harbor Freight just to give it a try, and ordered a QCTP from them also, not knowing there were much better ones in the same price range as the one they offer.  I thought I "had" to use that one since I knew basically nothing about machining.  If I could sell this one I would order me one with the cam lock on it from LMS, because on mine, you have to tighten a set screw in the side to lock the tool holder in.  I tried to get Chuck in E. TN to make me one with a cam lock....but he says he can't do it.  I thought a Master Machinist could do pretty much anything? ;)

[bp]

For what it's worth, I've read that a wedge clamp type is more secure and more rigid, than the (piston) cam lock type.
cheers
Bill

[Chuck in E. TN]

I'm a Master at several things, Dickey my friend, but Master Machinist is not on the list...
Save your pennies up and get an OXA from LMS. You won't regret it.

[vtsteam]

There's a very interesting set of articles on some unique very simple, yet solid tool holders by Robert M. Rose in Model Engineer vols 138 & 139 (1972 & 1973). I've long admired those even though I built a different sort. They do suit a carriage table -- which Myfords have.

I started building a boring table last year for the Craftsman lathe (Atlas type) with the idea that besides boring, it would be nice to try these tool holders, and one of Tubal Cain's Gibraltar tool holders, as well.

[velocette]

Hi
QCTP 's one of the most handy Mod's  I have done for my lathe. The problem with them that once they are established and a couple of tool holders fabricated.

The little buggers start to multiply and now I have a shelf full them with all manner of tools sticking out from them.

Over twenty of them at the last count. Perhaps some means of "Birth Control" is required.

Eric 

[Arbalist]

 

Shim shuffling is very last century.

Bill

So is a QCTP on a manual lathe but that's what most of us do as Hobbyists, if not we'd all be using CNC. 

[RodW]

I for one am not interested in CNC. I spend too much time on Computers as it is!

I think that for some repetitive applications, a rotating tool post containing all of the tools required for the job (shimmed to height of course!) might actually be quicker than a QCTP!

[philf]

I think that for some repetitive applications, a rotating tool post containing all of the tools required for the job (shimmed to height of course!) might actually be quicker than a QCTP!

Rod,

It might be marginally quicker once you've spent time shimming the tools but, in my opinion, the 4-way toolpost is still such a dangerous accessory with sharp tools stuck out everywhere. Give me my quick change tool holders any time.

Phil.

[Bigbadbugga]

I think that for some repetitive applications, a rotating tool post containing all of the tools required for the job (shimmed to height of course!) might actually be quicker than a QCTP!

Rod,

It might be marginally quicker once you've spent time shimming the tools but, in my opinion, the 4-way toolpost is still such a dangerous accessory with sharp tools stuck out everywhere. Give me my quick change tool holders any time.

Phil.

That was my thoughts too, and now that I have my mill I plan on making a quick change as one of my first projects. I like the looks of this one....

http://homepage3.nifty.com/amigos/qctp/qctp-e.htm

Although the sizes seem way off, either that or it's for a tiny lathe.

[PekkaNF]

I think that for some repetitive applications, a rotating tool post containing all of the tools required for the job (shimmed to height of course!) might actually be quicker than a QCTP!

If you have a good size lathe (toolpost), most of amateur lathes (that need this toolpost type thinkking process) are so small that the TP can fit confortably two shanks. Maybe four if you are lucky and are willing to use short pieces of HSS and use rear tool post for parting off.

Some people even make two or three rotating tool post uppers to get best of it approching QC tool post idea. Some have planned triangular rotating tool post to prevet porcupine effect.

Sometimes I would rather take gang TP or revolving TP, but same way than in capstan lathe. I haven't got so much repetitive work, but I have got pretty close some times.

Anyways, I think that whatever choice is taken it should fit the work you do most, because every eventuality can not be guessed untill you get stuck.

Pekka

[vtsteam]

Probably nobody looked up the ME reference, but to explain, the earlier toolholders I mentioned don't actually use a toolpost per se. They are separate tool blocks that get clamped down onto the carriage table. The clamp could be a quick acting one.

The nice thing is that the tool block can be oriented in any way or position -- it isn't tied to a post, and it also has the highest level of stiffness since there is no post and it can be positioned ideally on the table for the cut.

It also appeals to me because of its simplicity. I wish I could reproduce the articles here rather than just reference them in old ME issues.

[BaronJ]

I think that for some repetitive applications, a rotating tool post containing all of the tools required for the job (shimmed to height of course!) might actually be quicker than a QCTP!

Rod,

It might be marginally quicker once you've spent time shimming the tools but, in my opinion, the 4-way toolpost is still such a dangerous accessory with sharp tools stuck out everywhere. Give me my quick change tool holders any time.

Phil.

Believe me !  I've  got  the scars  to prove it.  A fraction of a second...  Its too late 
 

[Jonny]

I think that for some repetitive applications, a rotating tool post containing all of the tools required for the job (shimmed to height of course!) might actually be quicker than a QCTP!

Not only quicker but more substantial as in no movement.
Used to run a 140 with three 4 way posts and interchangeable with quick release on T slot. Did same on previous two lathes easy to get on centre for boring bars just drill with mill cutter of same diameter to leave required bore size.

What I did miss is 90 degree indexing, certain tools need to be square but didn't want to be held back by that none infinite adjustability.
You can only do repetitive stuff if you have a datum to work from.