370 forum posts
in another thread I have this photo. It is a vice I am adapting so I can hold work for milling in the lathe. I am planning on using a flycutter to put a 'flat' face on the front of that casting. I need the face to be parallel to the fixed jaw of the vice and both to be perpendicular, in this instance, to the face of the cross slide. So, how do I check that the fixed jaw face is at 90 degrees to the cross slide as there is limited space to get at the vice face and the cross slide. It is the technique and the tool to use that is beating me. I would expect that putting an engineers square onto the cross slide and trying to get it upto the face of the fixed jaw on the vice is the obvious answer though more difficult in practice due to lack of space. Then if I find the whole lot is out of square how do I adjust it and hold it securely while I run a fly cutter across the casting? Any advice is very welcome😀
Edited By Neil Wyatt on 08/07/2017 21:48:38
|Will Bells||08/07/2017 21:14:41|
|152 forum posts|
The classic method, if I understand the request correctly (Saturday night wine, not your description) is to use a dial gauge.
So hold a parallel in the vice jaws and set up a stationary dial gauge touching it, perhaps by putting the magnetic base on the lathe bed.
There is a theoretical error in that all lathes are supposed to face very slightly concave on extremes of tolerance, but hey, it's only small.
You need to clamp the casting to the cross slide with Tee bolts and clamps etc. and tap the casting progressively to true it up. Bit of a chew, but the only way.
It will take a lot of time to fly cut that lump off with the lathe.
Good Luck - Will
|Will Bells||08/07/2017 21:28:56|
|152 forum posts|
And ...... if you mean vertically, as in the horizontal as seen in the photo, a dial gauge on a mag base attached to the chuck moving against the parallel held in the jaws will detect that error as well.
Cheers - Will
985 forum posts
If you don't have a clock gauge, how about chucking a good piece of bar in the 3 jaw, or even better turn a bar parallel between centres. Then clamp the base end of an engineer's square in the machine vice at centre height, offer the blade up against the captive bar, and nip up the clamping bolts when it's parallel.
17073 forum posts
Flat bar or parallel in the vice, stand your tri square on the cross slide and check the bar in the vice is vertical.
Second oprion is to clamp say a bit of 1" square stock to the cross slide, dial it in across the lathe then with your vice upside down tighten onto the squarte bar.
3974 forum posts
... and when clamping your parallel in the vice, put a piece of round stock, say about the size of a pencil, between the moveable jaw of the vice and the parallel. This will ensure the parallel is pushed up against the fixed jaw and give a true reading of the position of the fixed jaw. Otherwise, the moveable jaw can tilt out of square vertically and allow the parallel to sit not quite dead true to the fixed jaw.
|Martin Connelly||09/07/2017 08:57:24|
959 forum posts
I second the second method proposed by Jasonb, maybe with a larger piece than 1". You can clamp the bar in place and clean up the face of it with a fly cutter to get the best possible reference face. You can set the vice on the bar at the best height for your fly cutter. I would support the overhanging weight of the vice as well. It has been proposed that a round bar is used against the movable jaw but a ball bearing would be the best way of ensuring the fixed jaw is tight against the reference face of the bar.
370 forum posts
Brilliant, thank you guys, multiple options for me and i can understand how they will all work
Will: I am opting for the fly cutter as I am thinking that as I don't have a vertical slide yet using a small diameter end mill will be out as I cant make succesive passes and raise the work height with each pass. I'm not sure the lathe is man enough to use a cutter with a large enough diameter, about 30mm, to do the job in one pass ??????
|Phil P||09/07/2017 11:56:36|
|592 forum posts|
+1 for Jasons upside down method, I was going to suggest it until I read the whole post and saw Jason had beat me to it.
I use that method when fitting a tenon to a vice base for aligning it to the tee slot on the milling table.
|John McNamara||09/07/2017 15:18:44|
1311 forum posts
I guess the question really is how do I align the vice fixed jaw to a plane at ninety degrees to the axis of the spindle. The alignment of the vice jaw must be both vertically and horizontally in line with the plane. The plane will later be the path swept by the cutter or fly cutter.
On method that would work quite nicely would be to remove the 3 jaw and replace it with a face plate assuming you have one. You could then fit a dial indicator or pin with a rounded end on the face plate at the diameter that allows the measuring device to clear the vice as it is swept, A small bracket or fixture made from scrap maybe. to hold it.
If you don't have a face plate then make up a crank and fit that in the 3 jaw, attach the indicator to that.
If you don't have an indicator a piece of feeler stock could be used to check the gap at the end of the pin, testing at various positions for a similar tension.
You will also need a piece of material of known flatness to fit in the vice jaw Long enough an wide enough for the indicator to run on over its sweep of 180 degrees.
This method cancels out any error in your face plate because you are measuring 2 points at 180 degrees
So your vice will be aligned in 2 planes.
|Howard Lewis||09/07/2017 18:44:13|
|2738 forum posts|
Would it be possible to clamp a piece of say 1" x 1" (25 x 25mm) to the front of the Cross Slide, (I would suggest drilling it and using studs and T nuts, if possible). Using the flycutter, skim it until it cleans up. You have now generated a face which is vertical, and at 90 degrees to the spindle (Or as square as the Cross Slide travel is) Once this has been done, without moving the piece of metal, with the vice upside down, clamp it to the just machined metal. The fixed jaw of the vice will now be vertical and square to the Spindle. Then you can fly cut your reference face on the front of the vice body.
Bob is now your mother's brother, as they say.
17073 forum posts
Howard that is what has been said above, first by me, 2nd by Martin and then by Phil
370 forum posts
John: Thank you, an interesting range of techniques; fortunately I have a dial gauge
Howard: Thank you also
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