I'm just starting out with machining, and I bought myself a cheap Chinese vice. Yes, I know, I know. Shoulda bought a Kurt. I didn't think the Chinese one would be that bad, and hey, it looked good in the catalog! I actually ended up with two, as one supplier forgot to cancel my order after I called, so he gave it to me at cost.
So I've got two Chinese vices. One looks better than the other. The second is an even worse casting than the first, the grinding is pathetic, and the fit and finish is sloppy.
After having a little trouble squaring up some material in it, I took a few minutes to run an indicator over the nice looking one and found something like 0.005" side to side across the bed and 0.014" variation overall. The ugly one is only out a few thou.
I did a little looking around for information on what sort of luck people have had with fixing up their junk vices. I found very little, but I did find this which was very helpful.
http://www.docsmachine.com/projects/4vise/4vise-01.html
My vice was a bit better built than this guy's, but was out much more in tolerances. I figured this would be good opportunity to learn and practice a little. I made a plan to disassemble the components and cut them down to flat and parallel with a 2" face mill (don't have a fly cutter yet). I don't have a surface grinder so I tried looking into options to make do with what I have to clean things up. After reading a bunch about how everyone says not to grind on a milling machine, I decided I'd try it anyway and mitigate as much as I could by taking it easy, covering up the ways really well, and vacuuming lots.
I used a 4" cup to grind. I cut the head off a 5/8" grade 8 bolt, threaded it onto the cup with a lock nut, and chucked it in the spindle with a collet. I was surprised at how true it actually ran.
It worked OK. Not ideal, but OK. It tends to clog quickly, even worse with coolant, and is not quick at all. It took a lot of time working slowly over the surfaces. I learned that when it starts making good contact, there's a lot of grinding surface touching metal, and builds up a fair bit of friction, and therefore heat. The heat is a factor and I was surprised at how much the CI moved.
I found that I had to work in the tenths range with the cup, and the heat generated definitely moved the CI a few tenths. I found that I could work with that and control heat build up by varying my feed. If I let the cup linger a little longer in one spot, the metal would swell up and the cup would dig in a little more. Towards the end, I was controlling this to my advantage instead of fighting it. It was pretty neat.
There's a reason that surface grinders use a wheel in a vertical orientation. The flat cup is not ideal, but I did get it to work OK. I cleaned and vacuumed lots because I was really nervous about grit and CI in the mill's ways. So it does work in a pinch, but it's not something I'm going to make a habit of.
In the end I got everything nicely trued up. I'm within half a thou for parallel and square and straight. I can live with that. I didn't do much with the movable jaw, just cleaned up the sliding surfaces and that angle that the little half-ball fits against with a file. There's still no question that it's a cheap Chinese vice; it' no Kurt, that's for sure. But at least now I've got a level base to work from. I've got about 10 hours into it, I could do it in half that if I were to do it over, and I'm sure you pros out there could do it in half that again.
Here's a little video of how it went.
[video=youtube;oKXyd78lcR4]https://www.youtube.com/watch?v=oKXyd78lcR4[/video]
So I've got two Chinese vices. One looks better than the other. The second is an even worse casting than the first, the grinding is pathetic, and the fit and finish is sloppy.
After having a little trouble squaring up some material in it, I took a few minutes to run an indicator over the nice looking one and found something like 0.005" side to side across the bed and 0.014" variation overall. The ugly one is only out a few thou.
I did a little looking around for information on what sort of luck people have had with fixing up their junk vices. I found very little, but I did find this which was very helpful.
http://www.docsmachine.com/projects/4vise/4vise-01.html
My vice was a bit better built than this guy's, but was out much more in tolerances. I figured this would be good opportunity to learn and practice a little. I made a plan to disassemble the components and cut them down to flat and parallel with a 2" face mill (don't have a fly cutter yet). I don't have a surface grinder so I tried looking into options to make do with what I have to clean things up. After reading a bunch about how everyone says not to grind on a milling machine, I decided I'd try it anyway and mitigate as much as I could by taking it easy, covering up the ways really well, and vacuuming lots.
I used a 4" cup to grind. I cut the head off a 5/8" grade 8 bolt, threaded it onto the cup with a lock nut, and chucked it in the spindle with a collet. I was surprised at how true it actually ran.
It worked OK. Not ideal, but OK. It tends to clog quickly, even worse with coolant, and is not quick at all. It took a lot of time working slowly over the surfaces. I learned that when it starts making good contact, there's a lot of grinding surface touching metal, and builds up a fair bit of friction, and therefore heat. The heat is a factor and I was surprised at how much the CI moved.
I found that I had to work in the tenths range with the cup, and the heat generated definitely moved the CI a few tenths. I found that I could work with that and control heat build up by varying my feed. If I let the cup linger a little longer in one spot, the metal would swell up and the cup would dig in a little more. Towards the end, I was controlling this to my advantage instead of fighting it. It was pretty neat.
There's a reason that surface grinders use a wheel in a vertical orientation. The flat cup is not ideal, but I did get it to work OK. I cleaned and vacuumed lots because I was really nervous about grit and CI in the mill's ways. So it does work in a pinch, but it's not something I'm going to make a habit of.
In the end I got everything nicely trued up. I'm within half a thou for parallel and square and straight. I can live with that. I didn't do much with the movable jaw, just cleaned up the sliding surfaces and that angle that the little half-ball fits against with a file. There's still no question that it's a cheap Chinese vice; it' no Kurt, that's for sure. But at least now I've got a level base to work from. I've got about 10 hours into it, I could do it in half that if I were to do it over, and I'm sure you pros out there could do it in half that again.
Here's a little video of how it went.
[video=youtube;oKXyd78lcR4]https://www.youtube.com/watch?v=oKXyd78lcR4[/video]
