Boring tool question

[borjawil]

Picked up my first lathe, a logan 200, and I have started to play around with the gearing and tooling. One of the things I got my lathe for was to turn spacers. So I need to be able to bore an ID. I have a 4 way tool post, but I am uncertain of what I am looking for in order to bore the spacers I will need. The ID of the spacers won't exceed 1.5". Do I need a round boring bar tool post? Are their tools for my 4 way post? How do I know what I need?

 

[MozamPete]

I've just been using a simple insert boring bar like this in a 4-wat tool post and I'm pretty happy with the results I get.


The shaft has a flat on the top and bottom so it sits in the 4-Way tool holder fine without any additional holder. Just need to get the correct diameter bar to suit your required tool height (so you don't need to use any packing to bring it to height)

 

[chips&more]

Welcome, you did not say how thick the spacers are? If thin, you can just grind a square HSS tool bit into the shape needed to bore it out…Dave.

 

[mikey]

It would help to know the depth of the bore. The ID only tells you the size of the bar that you must have to fit in the starter hole and still clear chips. The depth of the bore determines what material the bar is made from and the size the bar must be. For example, if you have a 3/8" boring bar and need to go only 1.5" deep then a steel bar is fine, but if you have to go deeper than that then a carbide bar will be better.

As Peter said, you can buy inserted bars with flats on two sides. You can also use sleeves with flats on the sides and a slit down one side to surround a round bar; this is far more rigid and also prevents marring an expensive bar. See what this guy did: http://www.micro-machine-shop.com/boring_bar_adapter_2.jpg

The problem with a 4-way tool post is getting the tool on center; you have to shim the tool. I'm sure you'll hear it from others but a quick change tool post will make this much easier for you.

 

[borjawil]

Wont need to bore deeper than 1 to 2" most likely. 1" or less would be more common.

 

[Wreck™Wreck]

Minimum diameter and depth of bore.

You can't stuff a 1" diameter bar in a 3/8" hole any more than then you can bore a 1" deep hole with a bar that has a 1/2" depth.

One may try but this rarely works.

Buy what fits your needs, no more or no less.

 

[mikey]

Look at the largest drill bit you have and size the bar you choose so it can go in that hole. For example, if the largest drill you have is 1/2", then you can get a 3/8" boring bar into that hole and it will work fine. For that matter, even the cheap Chinese brazed carbide boring bar sets that you can get for $10.00 will work for you. If you want an inserted tip bar then that will involve more homework for you.

 

[borjawil]

I saw the cheap boring tools for $12 and even I with no knowledge thought, there is no way those can be worth it. But I suppose Ill give it a shot. I also have a friend who works with everything from small lathes to huge lathes who probably has some tooling I can probably buy or borrow.

 

[mikey]

I would invest the $10-12.00 and buy one of those cheap brazed carbide sets and then use a diamond stone to sharpen each one. Make or buy a slitted sleeve and try it - I suspect you'll be surprised at how well the work. You cannot go deep with them but you can go to 1.5" with the largest bar. Use high speed with them and keep your depths of cut reasonable - maybe 0.020" max - and they will cut for you.