Installing a wedge QCTP on the HQ800V

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Torch
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Installing a wedge QCTP on the HQ800V

Post by Torch » Thu Aug 12, 2010 12:28 am

Note: most of this will be old hat to anyone with experience. I wrote it for other newbies like me who are confused by the whole topic.

Over the past few months, I read all about the advantages of a quick change tool post and the various types available. I eventually decided I wanted a wedge type, which are reputed to lock in more solidly than the piston type as the wedge pulls the holder in and down. I looked at making my own, but decided my skills weren't there just yet; tool holders I'll attempt, but the QCTP itself is something I resigned to purchase. I read about the pros and cons of Chinese and Indian offerings vs the expensive brands and decided to risk an inexpensive ($130) Chinese one from e-Bay.

Comparing the dimensions of the various sizes to the dimensions of the 800V, I determined the best fit would be the BX / 200 series size. The base is the right area for the compound and the height should readily position any height tool on centre. The only fly in the ointment was the fact that the mount would need to be modified.

Here's the stock parts, with the base removed:
Image

Removing the base is a simple matter of unscrewing the large flanged nut from the top. The rod is threaded 5/8" NF on both ends. The entire wedge assembly then lifts right off as a unit.

Of course, being a curious fellow, I wanted to see how it worked. With the base removed, the wedges can retract all the way off:
Image

From the side, you can see the worm screw. Turns out this is a multi-start thread and unscrewing it far enough to remove the wedges qualifies as a Bad Idea(tm). Kind of like removing the jaws from a chuck without knowing which one goes in which slot. Now we have to experiment to find the right combination so that a) the wedges rise and fall in unison and b) the lever ends up in a good place -- as in, not directly over the wedges when trying to change tools! So do yourself a favour and leave them where they are. Satisfy your curiosity from the picture:
Image

Ok, back to the installation then. Step one was to unscrew the centre MT rod and drill out the threaded hole to 5/8" -- same diameter as the rod. Also, I drilled and tapped a bolt hole to accommodate a key:
Image

A slot, sized the same as the compound slot, was milled in the underside to accept the key:
Image

Next, I turned down the end of the MT rod to a couple of thou under the same width. A few more thou off the end allowed me to thread it for 7/16 NF:
Image

This will allow the rod to pass through the compound t-slot:
Image

A custom t-nut was milled from CRS to complete the package:
Image

Another option I considered was to simply cut the threads off the end, and turn a groove in the MT rod. However, that wouldn't have left much up top for the big nut and it wouldn't provide as much contact area as a t-nut:
Image

Here's all the parts, as modified:
Image

And assembled:
Image

Ok, with the wedges correctly assembled to the worm screw, here's where the handle ends up when locked:
Image

and unlocked:
Image

The post came with a selection of toolholders. From top to bottom they are: 202, which is just like 201 (below) except with a groove in the bottom so it can also accommodate round tools like boring bars. 201 is the basic plain-jane tool holder for square tools up to 1/2". It will take a tool on either end, so you could put a turning tool on one side and a facing tool on the opposite end. 204 accepts 1" shank boring bars, with a sleeve to adapt 3/4" shank bars. 207 is a parting tool holder. Oddly enough, while the other holders accept up to 1/2" tool bits, the parting tool holder accepts up to 11/16" blades and is too big for 1/2" blades without a shim or two. Guess I'll have to buy some bigger blades. Finally, 210 is a weird combination knurling tool and facing tool holder (not sure if I'll ever use the knurler, I have a scissors type already):
Image

Shortcomings:
1. Allen key setscrews on the toolholders. I can see where those are going to fill with chips eventually. I like the square headed setscrews on the original turret post. I think I'll make some to fit these toolholders.

2. it needs something with a lever to replace that nut on top. It's a PITA to keep reaching for a 1" wrench to change the tool angle.

3. I need to figure out some way of indexing the angle of rotation. It would be nice to have a positive stop when square and at least at 29° (for threading).

On the plus side, the wedge action is exactly as advertised: with the locknut loose, the adjuster is easily turned to quickly fine tune the height. But when the lever is locked, the adjuster is snugged right down against the toolpost and cannot be turned by hand. The locknut is really just necessary to prevent inadvertent changes when the holder is kicking around the tool box.

Oh, and did I mention how quick and easy it is to fine tune the height? Actually, I'm kind of glad I spent the first 6 weeks wrestling with shims every time I needed to change tools. I now fully appreciate just how quick and easy it is to fine tune the height. Perfect facing with no shims!
Image

For those trying to figure out what tool fits different machines, here's the dimensions sent to me by the factory:
click here
click here

For those still confused by the whole "BXA / 200 series" designations, here's what they mean:

The "AXA" type designation is Aloris sizing. Yuasa, Phase II, etc. use 100, 200, etc.

AXA = piston type = size 100 (2 1/2" wide, 14mm dia t-nut) = 1/2" tool bit, 3/4" boring bar = model 250-100 .

AX = wedge type version in size 100 = model 250-111

BXA = piston type = size 200 (3" wide, 16mm t-nut) = 5/8" tool bit, 1" boring bar = model 250-200

BX = wedge version of size 200 = 250-222

CXA = piston version of size 300 (3 1/2" wide, 18mm t-nut) = 3/4" tool bit, 1" boring bar = model 250-300

CX = wedge version = model 250-333

CA = size 400 (4" wide, 22mm t-nut) = 1" tool bit, 1 1/4" boring bar = 250-401

DA = size 500 = 250-501

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ken572
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Re: Installing a wedge QCTP on the HQ800V

Post by ken572 » Thu Aug 12, 2010 6:12 pm

Hey Torch,
Very well done indeed. (Great Read)
Ken.
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

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Re: Installing a wedge QCTP on the HQ800V

Post by o1marc » Fri Jan 25, 2013 10:50 am

I don't think my compound tool post will be able to close to a width to accept just the tool bit. So it looks like I will be using the mill portion to modify parts just to enable me to use the lathe , that sucks.
When loosing the handle there are 4 detents and a spring loaded ball in the base to allow clocking in 90* increments. I'll study the mods you posted Torch and see where I need to go from there.

Torch
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Re: Installing a wedge QCTP on the HQ800V

Post by Torch » Sun Dec 08, 2013 9:17 am

One of the advantages of a wedge QCTP over a piston is repeatability -- that is, the tool tip will end up in exactly the same place when swapping it in and out. Generally I have found this to be true, at least for regular lathe bits that don't stick out very far.

However, yesterday I discovered there is a limit, at least, on this model when used with a long boring bar. I found it can vary up to 0.0015" (total, ie: +/- 0.00075") at the tip when removed and replaced. This was on the far side wedge, so maybe I had a fine chip in there that I missed wiping off or something. I was making several pieces requiring a press-fit for a bearing and found I had to slightly adjust the DRO each time I removed and replaced the boring bar. If I was just boring some bolt holes it might not matter, but that much variance is the difference between a nice press fit and the bearing falling out!

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warmstrong1955
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Re: Installing a wedge QCTP on the HQ800V

Post by warmstrong1955 » Sun Dec 08, 2013 1:19 pm

Torch wrote:One of the advantages of a wedge QCTP over a piston is repeatability -- that is, the tool tip will end up in exactly the same place when swapping it in and out. Generally I have found this to be true, at least for regular lathe bits that don't stick out very far.

However, yesterday I discovered there is a limit, at least, on this model when used with a long boring bar. I found it can vary up to 0.0015" (total, ie: +/- 0.00075") at the tip when removed and replaced. This was on the far side wedge, so maybe I had a fine chip in there that I missed wiping off or something. I was making several pieces requiring a press-fit for a bearing and found I had to slightly adjust the DRO each time I removed and replaced the boring bar. If I was just boring some bolt holes it might not matter, but that much variance is the difference between a nice press fit and the bearing falling out!
Yup...first one I had was a piston. Got it when I didn't know better. Wasn't much for repeatability either. Other problem was, it didn't like intermittent cuts, and would come loose if I didn't keep slappin' the handle to keep it tight. I broke it off at the threads a couple times.

I have an air hose on my lathe, and clean the post & the tool-holders off between changes. If I'm using oil, and things are messy, I'll wipe things down too. I made a paperweight instead of a bushing one time, for the very reason you're talking about. I had a 1" boring bar hanging out of the holder about 5". Doesn't take much of a chip to foul that up.

Bill
Today's solutions are tomorrow's problems.

Harold_V
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Re: Installing a wedge QCTP on the HQ800V

Post by Harold_V » Mon Dec 09, 2013 12:17 am

warmstrong1955 wrote:I have an air hose on my lathe,
I will be succinct.

I don't know how anyone gets along without air on the machine.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

Torch
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Re: Installing a wedge QCTP on the HQ800V

Post by Torch » Mon Dec 09, 2013 10:33 am

Harold_V wrote:I don't know how anyone gets along without air on the machine.
Ok, well I have been relying on shop towels and rags up until now. So maybe I should run a line over to the machine. Actually, this deserves it's own thread in the general discussion area. I'll wander over there.

John R
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Re: Installing a wedge QCTP on the HQ800V

Post by John R » Fri Apr 21, 2017 12:58 pm

Just to be sure I'm buying the right one is this what I want? I will be putting it on a Grizzly g9729 3 in 1 machine.

http://www.ebay.com/itm/BXA-Quick-Chang ... Sw9~RXJYCd

Torch
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Re: Installing a wedge QCTP on the HQ800V

Post by Torch » Fri Apr 21, 2017 1:17 pm

That looks like the same one I have. Note that I made further modifications later on, as documented in this thread:

http://www.chaski.org/homemachinist/vie ... 27&t=91868

John R
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Re: Installing a wedge QCTP on the HQ800V

Post by John R » Fri Apr 21, 2017 2:40 pm

Thank you I'm going to make one of those plates. How thick is it do you recall?

spro
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Re: Installing a wedge QCTP on the HQ800V

Post by spro » Fri Apr 21, 2017 5:27 pm

Hey. I don't know about that but maybe consider the AXA. These toolposts are horses The very first thing is measure the height of the compound to the center line. As these tool posts become larger they are wider and set the cutting tool further away from the strong axis presented by the saddle and slides. It may be a tighter circle allows a 5/8 or 1/2" tool holder to remain adjustable through a wider range. They are all using the same bits and biting the metal is the point. That requires more than a large tool post and rigid tooling, it is how it relates to the machine.

Torch
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Re: Installing a wedge QCTP on the HQ800V

Post by Torch » Fri Apr 21, 2017 6:44 pm

I didn't recall, but I just went out and measured. It's 0.550" thick. If I was making it again today I'd go a bit thicker though -- up to 0.750". It's Ok for 1/2" and 3/8" bits, but a touch low for 1/4" bits.

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