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Ogberi's Taig QCTP

ogberi

Active User
Active Member
#1
Hi All,

After cleaning up my lathe, I got started on making another QCTP. Before anybody starts drooling too much, it's not a wedge or piston type QCTP. It's literally a post mounted on the cross slide that toolholders slip over and are secured with a knob. (or a nut, in this case, until I can cast the brass knob)

The stock Taig toolpost is 1.75" tall, 1" square. The tool slot is 1" from the bottom, and it's secured to the cross slide with a 10x32 SHCS. While it's not a bad design, I hate when the SHCS for removing it gets plugged with chips. The grub screws that secure the cutting tool get full of chips too. Grabbing a T handle hex wrench is quick, but digging out the chips with a pick is a pain in the nether regions.

My design uses 1.25" square stock, around 2" tall, with the slot at the same height as the stock toolpost.

The toolpost itself is a 1/2" stainless steel bolt, which will have two tabs on the bottom to engage the T slot and prevent twisting. It'll be drilled down it's length to clear a 10x32 button head cap screw, and a 10x32 square nut will secure it to the cross slide. The upper end of the bolt is already threaded, and will stand proud of the top of the toolpost high enough for the knob to engage at least 3/8" of threads.

The toolholders will be drilled then bored for a slip fit on the toolpost. One end gets faced, then the drilling and boring (ensures it's perpendicular to the bottom), then it's flipped end-for-end and faced to length.

The second type of toolholder has tabs on it's bottom, to engage the T slots of the cross slide. This lets me position it at a known, repeatable angle to the spindle. Useful for boring and parting operations.

I started by chopping the stock to length with the mitre saw. I use a carbide-tipped Diablo blade on it (brand new), and aside from making a god-awful racket, it cuts quickly, square, and accurately. Stand to one side, wear safety goggles, and beware hot chips. Can you see the QCTP in here? I can.
TDSC_0089.JPG

You can see the longer blank. It's the one that'll have tabs on the bottom.
TDSC_0091.JPG

I then chucked up the piece in the 4 jaw chuck, got it centered, then faced it off. Spotted, drilled, bigger drill, drilled, bigger drill, drill. I actually tried drilling one out to 1/2" as a trial, and while it's usable, it's a bit sloppier on the toolpost than I like. I'll stick to drilling undersize and boring to a slip fit. The shank of the 1/2" bolt is actually very consistent in diameter.

I only had time to get one toolholder mostly finished today, plus my gimp knee was screaming by that point. Way too much walking, standing, and moving.

Definitely beefier than the stock Taig toolpost. I have already cut the head off of the stainless bolt, but haven't machined the tabs or cut it to length yet. That'll wait until the toolholders are finished.
TDSC_0095.JPG

Unfortunately, I won't be doing any shop work this coming weekend (nov 8-9). I *finally* got an appointment for surgery on my knee on Friday the 7th, and it'll be at least a week before I can get back out in the shop. Not a major surgery, thankfully. Just a torn meniscus and probably some torn ligaments. I'm really looking forward to getting it fixed. No more hobbling around or sleepless nights. I might have some free time in the evenings this week, but can't guarantee it. After I get home from work it's dark (Thanks, daylight savings :angry:), and my knee is usually screaming. If I do get out there, I'll take more pics. Gotta put that DSLR to use!

TDSC_0089.JPG TDSC_0091.JPG TDSC_0095.JPG
 

Andre

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Active Member
#2
Good luck with your surgery!

Should be a good project, a Taig lathe is on my wish list. Cheap and precise with many mods.
 

ogberi

Active User
Active Member
#3
Hi All,

Recovering from my knee surgery (it went great!), and spent a little time in the shop this weekend.

I chucked up the toolholders in the 4 jaw chuck, then faced it off and spotted, drill, drill, drill.... repeat 6 more times. I'm always amazed at the sheer volume of chips a project produces. I never bother melting them down, though. The surface area to volume is so high they oxidize before they melt. And you do *NOT* want to shove a compact mass of greasy, oily, chips into a pot of molten aluminum. Oil boils at considerably higher temperatures than water, but still *well* below the temperature of a crucible of molten aluminum. Cue explosion, spattering molten metal, numerous small fires, big cloud of stinking smoke from the cutting oils, etc. I used to just drop it off to the local recyclers. Never got much for it. Was "contaminated" aluminum.

Anyway, once I got all the parts faced and drilled, I set up the milling attachment. Zeroed that in, and began milling the slots. Used the dial indicator for the first one, then scrounged up some button cell batteries for my lathe's PMDRO (Poor Man's DRO, digital calipers mounted to the carriage and cross slide). Much quicker, as I needed to move in excess of 1" and my cheapie "1 inch" DI only has about .94 of travel. :/ Whoops.

At any rate, I got the tool slot milled in the first three short toolholders. The next two I'll get done this week, then I need to mill the tabs into the bottom of the long toolholders. After that's done, I can mill the tool slots in them. Drill and tap for the setscrews that bear on the tools, and the toolholders are done!

Then I do the toolpost work. It's actually pretty easy, just face off the bottom of the now-headless hex bolt, mill the tabs on it, cut it to length, slap it in the chuck and drill the #10 clearance hole. At that point I can mount my tools and get them on center, and start using it. Was going to post some pictures, but got the "over quota" message. Need to post more posts before I can post more pictures. Circular logic. :)

The project is moving along, my knee is healing, and I have pictures to post whenever I am able to. Meanwhile, I gotta go chime in on other people's threads to build up my quota.
 

ogberi

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Active Member
#4
Milled the slots in two more toolholders yesterday evening, now it's time to rotate the milling attachment and figure out how to safely mill the tabs in the bottom of the long toolholders. Nothing earth shattering. Although I must be an odd duck. I love the process of setting up almost as much as making chips. Snug the mounting bolts, measure, nudge, measure, nudge, measure, curse, nudge the other way, curse again, etc. It's just a feeling of satisfaction to see the DI sit steady as I traverse an axis.

The stainless steel toolpost might be an issue. It's tougher than boiled owl. Had to immediately sharpen my HSS tool as soon as it touched it. Bought a non SS 1/2" bolt as a backup in case the SS is too much for the little lathe. But, I think a razor sharp HSS tool should do it. Gotta find my diamond hones.

I doubt there'll be any work this evening. Temperature is currently ~46 at home, and will fall to the mid 20's overnight. Freeze warning, more than 4 hours of sub-freezing weather. Gotta unhook all the hoses from the bibs and put the insulator covers back on 'em. The shop is un-heated, and far too cluttered to put a heater in there. My old fire extinguisher had never been used, but the pressure was below the green on the dial, so I emptied it and will recycle it. No way in heck I'd save it as a backup. Never want the horror of grabbing a FE, pulling the pin, squeezing the handle and getting a lackluster "pfffft" that does no good whatsoever. FE's aren't cheap, but much cheaper than a new shop!

More posts to come as things progress! (and pics to come as I rack up some quota!)
 

ogberi

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Active Member
#5
Well, I got a bit more accomplished.

The toolholders are close to done. I need to make a jig to drill the holes for the set screws, and I need to order a proper BHCS for the toolpost.

But the stainless steel toolpost is done. I like it. It *barely* turned out wrong at the bottom, but it's an Uber-deep hole for such a tiny drill, so I forgive it. At least it's usable. Really usable, actually. :)

By my (probably wrong) estimate, I have around $35-40 bucks into this. At any rate, it'll work (proven), and new toolholders are as cheap as a stick of 1.25" square 6061-T6 and some time.

Anyway, I couldn't resist a mock-up. It ain't Mark F quality (in fact, he might chuck it in the bin and start over), but it'll work, I made it myself, and I'm proud of it. And it looks (and fits) better than my original of the same basic design.

As a side note - 99.99% of the work was done on my Taig lathe. I used a 3 jaw chuck, a 4 jaw chuck, a milling attachment, the tailstock with a 1/2" drill chuck (off a $1 cordless drill at a yard sale!), a blank arbor made into a 3/8" endmill holder, and a DTI. The only "other" tools I used were a sawzall to cut off the stainless steel bolt head and end of the threads. And a $40 Harbor freight mini-grinder to deburr edges and sharpen tools.

Can't wait to get it to a usable state and make some chips. Next up on my to-do list, is a tangential toolholder for my QCTP. Both round and square bits. Stay tuned for that, should be interesting! (at least to me).

Since a thread is worthless without pics, here's some pictures of the mockup. more pics to come as I do more work on this.

First pic - *CHIPS!!!!*
DSC_0116.JPG
DSC_0124.JPG
DSC_0125.JPG

DSC_0116.JPG DSC_0124.JPG DSC_0125.JPG
 

ogberi

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Active Member
#7
I like that idea, but I don't have the ability at the moment to cut the serrated disc. I'm sure I could figure something out, though. I simply replicated my old design because it works, and I'm familiar with it. I found an interesting chunk of steel that I think I may turn into a tommy-bar tightened oversize nut, once I get another couple of items off the to-do list.

Here's the toolpost itself - nothing dramatic, just a 1/2" stainless steel bolt, drilled clearance for a 10x32 screw. The tabs engage the T slot snugly and keep it from twisting while tightening down the 1/2" nut to secure the toolholder.
DSC_0160.JPG

Here's the toolpost mounted:
DSC_0161.JPG

And lastly, here's a tool in the toolholder. It works nice.

DSC_0162.JPG

I still have to re-grind a few tools before I can populate the other holders, and making more holders is definitely on the to-do list. But it's soooo dang nice to be able to switch tools in 10-15 seconds, vs the hassle of only having a single toolpost. I hate shimming tools, and at least now I only have to do it once per tool, until I re-grind it.

A tangential tool holder is in pre-production, just trying to remember where I put the piece of scrap I intended to turn into the toolholder...

DSC_0160.JPG DSC_0161.JPG DSC_0162.JPG
 

ogberi

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Active Member
#8
Hi Everybody!

I got a chance this evening to try out my new home-made tangential toolholder for my Taig's QCTP.

The toolholder is a bit "odd", in that it is inclined towards the workpiece and headstock by around 15 degrees. This allowed me to mill a corner down to hold the toolbit in position. A pair of button head screws secures the bit to the toolholder, and a grub screw underneath the toolbit allows me to both set the tool height, and prevents it from getting hammered lower in the toolpost by an interrupted cut.

Before I get my case jumped, yes, I realize I forgot my ring. Doesn't usually happen. Safety glasses were on. Excuse the wobbly bench, too. It's going to get replaced soon.

Took this video with my phone, had it propped up on the shelf above the lathe. Guess I need to bodge together a mount for it so I can get a bit better angles.

If there's any interest, I'll do some more videos.

http://youtu.be/CQ68T5V56F8
 

MarkStephen

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Active Member
#9
Is there any interest? Pfffftt.. Heck yes. Nothing wrong with more videos, and pics, and drawings, or at least some detailed pics with dimensions noted in the text.

Was there a reason you went with the nut on top instead of a clamp type setup? Nicely done with the tangential toolholder.

Mark
 
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ogberi

Active User
Active Member
#10
The nut is a temporary thing. Somewhere in my scrap box I've got a suitable piece of steel to make a more traditional looking clamping fastener. Just got to dig it out and get busy.

I still have one more tangential toolholder to make, this one to hold round toolbits. I don't think I'll need to make a slanted toolpost for it, though. It'll still have the grub screw in the bottom to set the height and prevent hammering, but it should only need a single grub screw perpendicular to the tool to secure it in the toolholder.

Next project is adding power feed to the leadscrew. Got more doodles done, some ideas in my head for it. Just need some shop time. Maybe this weekend.