Work holding on a micro lathe

cwr89

cwr89

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Hello all,
First post here and I'm and absolute beginner so, any and all advice is greatly appreciated!
I bought a Taig Mini-lathe about 2 years ago and I've been slowly learning to use it. Its a ton of fun, absolutely love the machine. I recently, in a desire for a bit more precision, got an ER-32 collet chuck for. Its totally changed my world. So much stronger and accurate than the 3 and 4 jaw chucks.
I also happened across a garage/estate sale from the family of an old union machinist. I bought his tooling for next to nothing. I realized that I can't use most of the lathe bits as I don't have any height adjustment on my stock toolpost. I found a youtuber who recently made a QCTP for a Taig specifically and had the plans available. With a set of plans, a good collet chuck, and a ton of end mills I figured, why not give it a try.

So, I'm working with 6061 Aluminum, 1" square stock. I'm using the Taig milling attachment for the lathe, and the small milling vise. I've been able to face off the square stock with no issue, but theres a few pieces that need some support with parallels. I just can't for the life of me get the parts clamped up squarely. -- I also have zero experience in any milling operation, its been more trial and error learning.

I don't have a set of parallels. Do they make any in micro-lathe-milling size?
The plans themselves use a bolt on style of dovetail, as it was designed for someone without a dovetail cutter. but I just can't seem to square it up.

This is my setup, which seems to work fine for parts that are large enough. (pay no attention to my very poorly placed indicator :oops:)
IMAG1006.jpg

And this is the part with the bolt on dovetail.
IMG_20170305_195112.jpg

Any thoughts at all would be greatly appreciated! Thanks!
~Casey
 
You can use HSS bits for parallels. The decent ones are ground square and parallel and pretty close to nominal size. Nice project, and welcome to Hobby Machinist!
 
Welcome, I hear you on your frustration! But, do you really need to be square? The OCTP or block has only one face with the screw on dovetail that is kind of important. It needs to hold the tool holder firmly and repeat to changes with precision. Maybe the bottom of the block to be square with that side we just talked about. Everything else is just cosmetic IMHO…Dave.
 
You can also use adjustable parallels. I see them on ebay quite often, you would only need a few of the smaller sizes.
 
TakeDeadAim said:
You can also use adjustable parallels. I see them on ebay quite often, you would only need a few of the smaller sizes.
Click to expand...

I suppose you could but I wouldn't buy adjustable parallels to be used for milling like normal parallels. Do people actually use them that way? Adjustable parallels are used as a measuring device.
 
Bob Korves said:
You can use HSS bits for parallels. The decent ones are ground square and parallel and pretty close to nominal size. Nice project, and welcome to Hobby Machinist!
Click to expand...

Thats absolutely brilliant! I'm still trying to wrap my head around milling on the lathe it self. Thats a great idea I have a bunch of unground, and still nicely polished HSS bits!


darkzero said:
LMS sells 1.5" & 3" long parallels.

http://littlemachineshop.com/products/search.php?tabName=Products&term=Parallels

I know you are making the QCTP but they also sell the QCTP & holders for Taigs.

http://littlemachineshop.com/products/product_view.php?ProductID=4039&category=-419988835
Click to expand...

I looked at LMS's QCTP for a very long time, and chances are [once I reduce the 8ft of aluminum stock I bought to chips] I'll buy one thats a proper tool. :D


chips&more said:
Welcome, I hear you on your frustration! But, do you really need to be square? The OCTP or block has only one face with the screw on dovetail that is kind of important. It needs to hold the tool holder firmly and repeat to changes with precision. Maybe the bottom of the block to be square with that side we just talked about. Everything else is just cosmetic IMHO…Dave.
Click to expand...

Where I'm running into the problem is that I'm not getting the face of the dovetail that mates to the actual holder parallel to the face that bolts to the post. The part was giving me a 3-5 degree angle in both the x and y planes. In the test fitting it was causing the mating dovetail to jam.


TakeDeadAim said:
You can also use adjustable parallels. I see them on ebay quite often, you would only need a few of the smaller sizes.
Click to expand...
I'll have to add these to the ever growing list of tools I probably should look into getting :)

This is all amazingly helpful info already! thanks a ton!
~Casey
 
Casey, if your milling vise is accurate and the milling attachment is 90 degrees and square to the bed of the lathe then you should be able to get most of the work square without parallels. I assume/hope you have checked the vise and milling attachment for accuracy, right?

If you want to mill stuff, you need parallels. The cheap short 3" ones linked to at LMS will not break the bank and are worth buying. I use HSS tool bits as parallels on occasion but for thin work, like your dovetail part, you need something that positions the part at the right height; I suggest you buy the parallel set and get on with it. (I use that set on my Sherline mill and they are fine for a Taig/Sherline-sized vise.)

Has it dawned on you that you need a milling machine yet? :confused:
 
My understanding is that the taig vise is less then great. Meaning it can do great work if you take care and precautions, or you can be a little lazier and faster with a vise upgrade.

I have no firsthand experience with the taig, hopefully one of those guys can chime in. Good luck
 
cwr89 said:
Thats absolutely brilliant! I'm still trying to wrap my head around milling on the lathe it self. Thats a great idea I have a bunch of unground, and still nicely polished HSS bits!
Click to expand...
'Trust but verify.' Measure those bits to make sure they are accurate enough for what you are planning.
 
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