- Joined
- Dec 27, 2014
- Messages
- 658
Ahhh, I see.
In theory, an R8 arbor mounted drill chuck will run more true than a straight shank arbor mounted drill chuck in a collet.
In practice, a good straight arbor in a good collet will be more true than the quill on your fine Taiwan mill, so you are already doing better than the machines tolerance. The R8 arbor will also give you a touch more rigidity, which is good to have when drilling large holes with no pilot. But, once again in practice, probably not needed. I just drilled a 1" hole with my 1/2" straight arbor mounted drill in 3/8" steel on my PM450G (it is smaller than the mill you are getting), and it just went right through it like nothing. An R8 arbor will also save a bit of wear and tear on the collet if you are going to do a lot of large hole drilling, so probably worth investing in if you will be doing a lot of this sort of work.
Trueness really counts when drilling tiny holes, but that is work for a sensitive drill anyway.
You will find that a pretty large number of us use a straight arbor in a collet and never even think about it, or it's limitations.
Regardless, there are many places that you can buy cheap Chinese tooling and get great results. In my opinion, drill arbors and chucks are not one of the places to get cheap. You will probably end up with an assortment of them anyways. I found 4 or 5 drill chucks when I moved the shop to the basement, they have a weird way of sprouting up in a back shelf corner.
As for my arbor, I have not decided what to do with it yet.
In theory, an R8 arbor mounted drill chuck will run more true than a straight shank arbor mounted drill chuck in a collet.
In practice, a good straight arbor in a good collet will be more true than the quill on your fine Taiwan mill, so you are already doing better than the machines tolerance. The R8 arbor will also give you a touch more rigidity, which is good to have when drilling large holes with no pilot. But, once again in practice, probably not needed. I just drilled a 1" hole with my 1/2" straight arbor mounted drill in 3/8" steel on my PM450G (it is smaller than the mill you are getting), and it just went right through it like nothing. An R8 arbor will also save a bit of wear and tear on the collet if you are going to do a lot of large hole drilling, so probably worth investing in if you will be doing a lot of this sort of work.
Trueness really counts when drilling tiny holes, but that is work for a sensitive drill anyway.
You will find that a pretty large number of us use a straight arbor in a collet and never even think about it, or it's limitations.
Regardless, there are many places that you can buy cheap Chinese tooling and get great results. In my opinion, drill arbors and chucks are not one of the places to get cheap. You will probably end up with an assortment of them anyways. I found 4 or 5 drill chucks when I moved the shop to the basement, they have a weird way of sprouting up in a back shelf corner.
As for my arbor, I have not decided what to do with it yet.