Rob Turbo
5th Jul 2016, 03:50 AM
I'm building a milling machine using the top bit of a Dore Westbury and an Axminster CT1 compound table, bolted to a 20mm thick steel plate.
The Dore Westbury has a hollow round column, 60mm diameter, with a thread to raise/lower the head. The problem I have is the column I have is rather short, it seems to have snapped then been filed, and it's in poor condition, heavily pitted with rust.
I managed to get hold of some thick walled 60mm O.D. steel tube, it seems to be the same spec as the original, but it's sort of egg shaped, the side with the seam is around 1mm bigger. My plan was to file one end round and put it in a fixed steady, hold the other end in a 4 jaw chuck set with a DTI around the round 3/4 then turn the high spot off the whole length, then turn it around to do the part that was in the chuck.
I also have a length of machined 64mm O.D. soild round bar, I have 2 options with this, first is turn the whole length down to 60mm, second is turn one end down to 60mm to fit into the head then make a new base, even though it's only 2mm all around I wouldn't trust the original base bored out, I think it's 2 separate castings welded together, the top half is plenty thick enough, but the bottom half doesn't fill me with confidence! When it comes to making a new base I have 2 options as well, bore a hole in a solid piece of steel which is the expensive option, around £80 for a big enough lump, second is fabricate one, a few pieces of 20mm plate bolted together, possibly welded, then bore a hole through, the materials for that are less than half of one solid piece.
Third option, 60x60x4mm box section (or bigger), make an adapter to fit into one end for the head then fabricate a base from 20mm steel plate. The beauty of this is it won't loose zero when it's raised/lowered, plus this is the cheapest and quickest way of doing it. The problem I have is will a hollow square column be as sturdy as a hollow round column? Will it crush when it's clamped?
Whichever option I choose, I won't be cutting a thread into it like the original, that seems like the weak spot (maybe why it snapped?), I'll be using a different method of raising/lowering it. It's only a small mill (MT2 in the spindle) so it's not like I'm expecting it to take huge cuts or anything, but at the same time I don't want it to be some flimsy useless machine, it's not pretty enough to sit there doing nothing!!
Which would you go for? Is there a better way that I'm missing?
Thanks,
Rob
The Dore Westbury has a hollow round column, 60mm diameter, with a thread to raise/lower the head. The problem I have is the column I have is rather short, it seems to have snapped then been filed, and it's in poor condition, heavily pitted with rust.
I managed to get hold of some thick walled 60mm O.D. steel tube, it seems to be the same spec as the original, but it's sort of egg shaped, the side with the seam is around 1mm bigger. My plan was to file one end round and put it in a fixed steady, hold the other end in a 4 jaw chuck set with a DTI around the round 3/4 then turn the high spot off the whole length, then turn it around to do the part that was in the chuck.
I also have a length of machined 64mm O.D. soild round bar, I have 2 options with this, first is turn the whole length down to 60mm, second is turn one end down to 60mm to fit into the head then make a new base, even though it's only 2mm all around I wouldn't trust the original base bored out, I think it's 2 separate castings welded together, the top half is plenty thick enough, but the bottom half doesn't fill me with confidence! When it comes to making a new base I have 2 options as well, bore a hole in a solid piece of steel which is the expensive option, around £80 for a big enough lump, second is fabricate one, a few pieces of 20mm plate bolted together, possibly welded, then bore a hole through, the materials for that are less than half of one solid piece.
Third option, 60x60x4mm box section (or bigger), make an adapter to fit into one end for the head then fabricate a base from 20mm steel plate. The beauty of this is it won't loose zero when it's raised/lowered, plus this is the cheapest and quickest way of doing it. The problem I have is will a hollow square column be as sturdy as a hollow round column? Will it crush when it's clamped?
Whichever option I choose, I won't be cutting a thread into it like the original, that seems like the weak spot (maybe why it snapped?), I'll be using a different method of raising/lowering it. It's only a small mill (MT2 in the spindle) so it's not like I'm expecting it to take huge cuts or anything, but at the same time I don't want it to be some flimsy useless machine, it's not pretty enough to sit there doing nothing!!
Which would you go for? Is there a better way that I'm missing?
Thanks,
Rob