School Me On Boring Bars And Holders

[T Bredehoft]

or you could make a broach.

Whew. there's a thought. Could I do it without any kind of controlled grinder? Hmmm. If my mill had a controllable Z, in tenths, maybe, but it doesn't. I've made several boring bars, to hold HS and carbide round tools, they work pretty well.

 

[churchjw]

You could make a passable broach from a lathe tool using just a free hand grinder. You may need a cut off wheel to get some of the angles. I guess it depends on how big a press you have and how hard it will push. There is nothing wrong doing it with a round HSS cutter. Could be a good use for broken center drills. end mill, or taps. Would that work? Never tried to use an old center drill or tap as a lathe tool. How does the steel compare?


Jeff

 

[Wreck™Wreck]

Use the largest bar that will fit in the bore (and your holders) and leave sufficient chip clearance, packing a bore up with chips rarely works well and will often damage the tool, the part or both.

Inexpensive round bars with a square hole broached through them for holding square HSS blanks with a set screw work well for hobbyist/one off work. The tool may be ground for internal grooving, internal threading and back boring Etc. Buy one that has a 45° hole in one end and a 90° hole in the other, the 45° will allow you to bore the the bottom of a blind hole.

 

[Wreck™Wreck]

You could make a passable broach from a lathe tool using just a free hand grinder. You may need a cut off wheel to get some of the angles. I guess it depends on how big a press you have and how hard it will push. There is nothing wrong doing it with a round HSS cutter. Could be a good use for broken center drills. end mill, or taps. Would that work? Never tried to use an old center drill or tap as a lathe tool. How does the steel compare?


Jeff

High speed steel taps work fine in a lathe as turning tools. Have used them in square hole boring bars in the past when the (Job Must Be Finished Today) and I had nothing else.

 

[markknx]

Great White as you see it can be quite an open subject when it comes to tooling. And I do not feel any of the above are wrong answers. You gave dia. What about how deep/long the bore is. If they are short then the sets for a boring head are OK. I think the range is like 1"-3" deep maybe 4". if you think you will be doing deeper bores then I would suggest longer bars. I would only go with Carbide if you need carbide.

If I nay be a bit forward, Learn to grind your own bits. you will see it is not hard to get good results, and it is much cheaper. A well ground bit kept honed will last a long time. You get many option of size and shape. You can even make boring tools. I a novice have even used a piece of drill rod to make a boring bit in a pinch. (took a few more spring cuts but it got me by.) It also opens up the repurposing of old broken drill bits, endmills, and the like. Could be if you are not boring deep you already have a few boring bars that are hiding in old broken tools.

Check you tube, Abomb, Mrpete, tom lipton and many others have good videos onhand grinding bits. On this forum there is a thread on it right now and it has a link to two vids on grinding. here

http://www.hobby-machinist.com/threads/turning-tool-and-facing-tool-questions.36687/page-10

I know you wanted to know about boring bars, but you did say you wanted to keep it low cost.

Mark.

 

[dave2176]

I use carbide insert holders almost exclusively. But I do have this set from Enco. (3/8, 1/2, 5/8, 3/4, 1.0) #378-4000 was in hot deals plus 20% and free shipping it cost $20.76. One end is angled, the other 90*. Add a few 1/8 and 3/16" HSS tool bits and it serves well.
Dave

 

[atlas ten]

You can try making them. I got couple home made ones with my lathe purchase. Previous owner welded hss chunk to mild steel square stock. Then ground to boring profile. I have made couple smaller also from broken off pieces hss. Do keep them small ones. Not sure how well they work but worth a try.
I did upgrade to qctp shortly after. Will use 3/4" bar with 1/4" hss
Jack