Squaring QCTP with compound - Atlas 618

Moto-Mucci · Apr 27, 2020

I recently bought a late model Atlas 618 and picked up the quick change kit from Little Machine Shop.

I’m having trouble bolting down the quick change post to the compound so that it’s perfectly square. I figure that way I can use the degree markings in the compound.

The T-nut that comes with the kit is a very loose fit in the compound. When I go to torque the post down it inevitably rotates. I’ve cleaned the mating surfaces with brake clean to make sure there’s no lubricant but it still moves when tightening.

I figure most of the processes don’t need this to be square but it’d be nice to have when using the parting tool so I can set it at 90.

Rob F. · Apr 27, 2020

Put the edge up against the chuck face.
Your thread will be closed for mentioning that brand of lathe, do not mention it in future posts, or ask on HSM.

Moto-Mucci · Apr 27, 2020

Rob F. said:
Put the edge up against the chuck face.
Your thread will be closed for mentioning that brand of lathe, do not mention it in future posts, or ask on HSM.

I can't tell if this is a joke or not.... What's the deal with Atlas. And what's HSM?

Hardplates · Apr 27, 2020

Machinery Discussion Guidelines

HSM = High Speed Machining = trochoidal toolpaths

PDW · Apr 27, 2020

Moto-Mucci said:
I can't tell if this is a joke or not.... What's the deal with Atlas. And what's HSM?

Discussion of brands like Atlas are not permissible here, along with cheap hobbyist machines of other varieties. Excepting cheap South Bends.

HSM - Home Shop Machinist, a forum for hobbyists.

PDW

thermite · Apr 27, 2020

Moto-Mucci said:
I can't tell if this is a joke or not.... What's the deal with Atlas. And what's HSM?

Discussing the equipping of an @las LSO (Lathe Shaped Object) with a "QCTP" is in the same class as publically ************************ grieveously abused camelids on the floor of the United States House of Representatives.

It's only a "joke" if you don't actually DO it, and the Congress critters DO!

michiganbuck · Apr 27, 2020

Discussion of brands like Atlas are not permissible here, along with cheap hobbyist machines of other varieties. Excepting cheap South Bends.

Somewhat because guys with such lathes ask such basic question because they wont take the time to read How to Run a Lathe or some other book to get past such question like how do I line up my...
That same question asked a few hundred times would make this site boring...but do read the book and come back with a problem with not mentioning the brand.

Here find a good example . This fellow uses a screw driver for an Allen wrench so not the best teacher.
See at 7:52...
YouTube

*A lathe hand would see many things he is doing wrong.

Still if you have an At you can learn lathe stuff on it... You tube can be good along with getting a book on running a lathe.

steve45 · Apr 27, 2020

michiganbuck said:
Here find a good example . This fellow uses a screw driver for an Allen wrench so not the best teacher.
See at 7:52...
YouTube

*A lathe hand would see many things he is doing wrong.

Still if you have an At you can learn lathe stuff on it... You tube can be good along with getting a book on running a lathe.

Not sure if the screws for the gibs are Allen or slotted, but regardless, he doesn't know what he's adjusting. He's got slop in the carriage leadscrew nut.

He'll lose some fingers, or worse, if he keeps sticking his fingers in a hole on a piece that is spinning. And adjusting the tool holder while the lathe is running? (Next video in the series). Then he has to drive the bit out of the tool holder and it's in sideways! That's when I quit watching. And I'm just a hobbyist.

Bill D · Apr 27, 2020

I use a 123 block off the chuck side or face. Please do not ask what is a 123 block.
Bill D

trevj · Apr 28, 2020

Moto-Mucci said:
I recently bought a late model Atlas 618 and picked up the quick change kit from Little Machine Shop.

I’m having trouble bolting down the quick change post to the compound so that it’s perfectly square. I figure that way I can use the degree markings in the compound.

The T-nut that comes with the kit is a very loose fit in the compound. When I go to torque the post down it inevitably rotates. I’ve cleaned the mating surfaces with brake clean to make sure there’s no lubricant but it still moves when tightening.

I figure most of the processes don’t need this to be square but it’d be nice to have when using the parting tool so I can set it at 90.

View attachment 286475

View attachment 286476

It may have occurred to you by now, that you are essentially putting lipstick on a pig.
No matter how good a job you do, it's still a pig!

I won't hold the QCTP from Little Machine Shop in much higher esteem either.

Aside from the underbuilt and flexible nature of pretty much all parts of that lathe shaped object, if the tee nut is too tall, and the middle clamps up solid before the edges do, that can be an issue. As can the threads being so fucked up that you cannot torque down on them and have the part stay in one place when you do so.

On that note, I wish you the best of luck, and that you get an opportunity to experience a decent working lathe a few times, before you give up in disgust for having chosen poorly from the outset.

Rob F. · Apr 28, 2020

Back to your original question, it looks like the tee nut is to tall and is "bottoming" out on the underside of the QCTP before it can fully grip the tee slot in your compound. You can test this by placing two sheet metal strips on the tee nut faces that should tighten on the compound slot. Make sure they are from the same piece of metal so thickness is the same.

Hardplates · Apr 28, 2020

Bill D said:
I use a 123 block off the chuck side or face. Please do not ask what is a 123 block.
Bill D

Everyone knows the 123 block is a disco dance you do when things need to be hyper accurate

michiganbuck · Apr 28, 2020

qt[be square but it’d be nice to have when using the parting tool so ]

The compound protractor is never close enough for a parting tool ..you have to touch the side to a face part end, or to your chuck face..it has to be dead square..even if you need to move your lamp or use a magnifying glass to make it so.

jim rozen · Apr 28, 2020

Moto-Mucci said:
I’m having trouble bolting down the quick change post to the compound so that it’s perfectly square. I figure that way I can use the degree markings in the compound.

Not needed. For facing you want the turning tool to be pointing a bit to the left for clearance. For turning, a bit to the right.
For grooving or cutoff, you square the tool with a freshly-turned face on the workpiece. Degree markings on the compund are hardly ever used.
As mentioned be sure the top part of your T nut is not oversize.

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