Boring on a Rotary Table?

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ShagDog

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I have a PM 728vt. I also have a rotary table. Don't have a boring head, and my drill only go up to 1/2" diameter.

Question is whether it is feasible to bore small holes like 1" diameter on a rotary table, as opposed to using a boring head on a small mill the size and weight of the PM 728.
 
Thanks. Now for the next question. Would rotary table boring be better( for such issues as chatter) than using a boring head? Actually, other than set-up, which is going to produce better accuracy and less chatter on a small mill?
 
For ease and accuracy a boring head would be better . On a RT , you're limited to one hole at a time without shifting your part if this makes a difference .
 
ShagDog said:
I have a PM 728vt. I also have a rotary table. Don't have a boring head, and my drill only go up to 1/2" diameter.

Question is whether it is feasible to bore small holes like 1" diameter on a rotary table, as opposed to using a boring head on a small mill the size and weight of the PM 728.
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Horror Fright has a set of drill bits HSS that go up to 1". Also the Boring head that PM sells is pretty reasonable and works well. Additionally, if you do have a rotary table, drilling a half inch hole then machining it to a larger bore with a small end mill works well also.... Smokem if ya gotem....
 
There's no reason you can't bore holes using your RT. However, to reduce chatter and milling problems due to backlash in the RT you want to make sure you are conventional-milling, not climb milling. That means using the correct direction of rotation of the RT. Since most end mills are designed to cut while cutting clockwise (as viewed from the top), that means you want to turn the RT counter-clockwise while milling the hole.

One disadvantage of using an RT is accurately placing the hole. It will end up being coincident with the RT's center of rotation so you need to mount the work as accurately as possible so the RT's center of rotation coincides with the desired hole's center. A boring head is easier to set up in this regard.

Boring through-holes also may be a bit more difficult to set up, to avoid damaging the top of the RT. A sacrificial piece would help there.
 
You don't say how deep the hole is to be, with end mills you are limited on the reach, and the deeper the hole, the more tendency to chatter, a boring head is the more practical choice for finish and accuracy.
 
Look into Silver and Deming style drills, which have a turned down 1/2" shank and can go over 1" in size. You won't get perfect holes but its the quickest way to remove material. Then use the Rotary table or boring head to finish up.
 
machPete99 said:
Look into Silver and Deming style drills, which have a turned down 1/2" shank and can go over 1" in size. You won't get perfect holes but its the quickest way to remove material. Then use the Rotary table or boring head to finish up.
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The HSS Bits set I mentioned at harbor Freight goes from 9/16" to 1" in 1/16" increments and all have a 1/2" shank. I have a set and they are very good for the price and the frequency of use, if I use them in a collet they produce a tight straight hole.

Sorry, forget to mention the 1/2" shank, I failed to thinks about that being important to some folks.
 
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