taig boring head

[bronson]

So a few months ago i ordered the new taig boring head it was pretty cheap to buy and i have owned a taig mill for a few years and have been happy with quality and thought it would be a nice addition. I used the boring head for the first time last night it worked well even with a cheap boring bar i was cutting through bronze, my only issue is that there is no way of knowing how much you move the offset or am i missing something. Any help with this would be welcome.
http://www.mechanicalphilosopher.com/taigborehead.html

 

[ttrikalin]

this is similar to my sherline boring head.

In mine the screw that advances is a 5-40. So One full turn is 25 thousands of radius. I have made a small disk with graduations, but it is clunky.

I will get a photo to show what I mean...

take care and happy new year,
tom in MA.

 

[bronson]

Thanks for the quick reply looking forward to the photo.

Happy new years.

 

[ttrikalin]

Here is what I meant... I have 25 graduations on a disk that is loctite'd on the 5-40 screw. One line is 0.001. A small dot marks an origin.

The obvious difficulty is the lack of a reference line to count from (like the 0 on a lathe dial). I use the slot that you see in the back, while eyeballing the boring head from this angle. This can easily result in a parallax error of 2-3 thousands, but if you are careful you can do well, i.e., machine to 0.001" or less. (E.g., verified by gage pin measurements)

Here is a lateral view. In my opinion, this boring head needs rethinking. It can be made to work, but the one Dean made is hands down better.

take care,
tom in MA

 

[GailInNM]

A magnetic base dial indicator works fairly well. Indicate the shank of the boring bar and rock the spindle to get a maximum reading. Make your adjustment and then rock the spindle again to check that the spindle has not moved while you were adjusting. Not as fast as direct reading boring head but it is accurate.
Gail in NM

 

[bronson]

Thanks for the quick replies and ideas i will give both a try and see what works best for me.

 

[Swede]

I don't know about other guys, but I simply don't trust my Criterion-style boring head when it comes to the graduations, and the best I can do is execute a lot of repetitive measuring using a telescoping bore gauge or pin gauge and try and sneak up on the final bore.

One way to correct this, although it can be tedious and sometimes requires a tooling change, is to find and use a "tenth's set" boring head. These devices have a different sort of mechanism allowing truly fine control. Most have a ring around the body with graduations down to 0.000,1" and they are very accurate. Unfortunately they are also really expensive when new, and I haunted eBay for months to find a decent one that fit in my budget. They also tend to have a limited range vs. a Criterion style.

Anyway, they are out there, and if someone does a lot of fine, precision boring, they are a nice investment.

 

[bronson]

Thanks for the heads up i will keep my eyes open for one like you described. What is the brand of the one that you found ?

 

[Florian]

Something differnet to what you were asking but I recommend to use HSS Boring bars because you can grind them sharper than those typical chinese-boring bars with Carbide tip.

And this results in better surfaces and less chattering compared to what is possible with those carbide-tipped boring bars.

Cheers Florian

 

[bronson]

I do have some really nice boring bars ground from hss by a locale guy called http://www.attacktool.com/home.htm he stuff works great.

 

[Florian]

Well, then i guess you will have no Problems with chatter marks

Cheers Florian

 

[Swede]

Thanks for the heads up i will keep my eyes open for one like you described. What is the brand of the one that you found ?

It is unmarked but I believe it is an Erickson.

Something to keep in mind (again) is the limited range of these devices. Often it is 1/2" or so, because the way it works is very different from a dovetailed Criterion. Basically, two angled hardened steel blocks slide to create the offset. They are really best used when you need to make a number of a particular bore size, like a multi-cylindered engine.