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clutch
01-30-2010, 05:19 PM
I spent a bit of time today trying to figure out how to measure the angle of my vee way that locates the carriage on my 6903 lathe.

Anyone know what it is? Anyone have down and dirty ideas on how to measure it? I'm thinking something like scissors with a pivot very close to the end for vee's that are not very tall coupled with a bit of trig.

I want to make a micrometer stop and cutting the correct angle to clamp it to the bed is why I need the dimension.

Ideas?

Clutch

Boucher
01-30-2010, 05:33 PM
I would guess that it is a 90°. Take a piece of cardboard like a file folder and draw a 90° notch on one edge and cut it out and see if it fits. If it doesn't trim it untill it does then measure that.

doctor demo
01-30-2010, 05:34 PM
Clutch, I'm not familiar with that machine, but if the ways are 90deg. You can check that against a V block. A vernier protractor would do it also. But if the V is greater than 90 , for a stop, 90 should be just fine as long as You get rid of any sharp corners. A stop is not as critical as the carriage and there will not be any wear,as it is not a sliding bearing.

Steve

Black_Moons
01-30-2010, 06:04 PM
I like these for being super precise about measurement:
http://www.robotroom.com/StreamHawk/Angle-Blocks-For-Machining.jpg

With a little oil they 'ring' togethor to stick, and being ultra precise ground with blocks of 1 degree and 5 degree (or 1/4 degree for some sets) (a set would be like 1 2 3 4 5 10 15 25 30 degrees.. no idea why they never seem to have a 35 40 or 45)

With these (And maybe a straight edge) its easy as pie to tell exact angles, even without the 1/2 degree blocks you can do better then 1 degree by just compairing visualy/by feel the fit, if 35 fits exactly, its exactly 35
if 35 and 36 don't quite fit (But one is too big and one is too small), you know its inbeween

McNeillMachine
01-30-2010, 06:22 PM
I have a 5914 and the vee is 70 deg included. maybe that helps?

clutch
01-30-2010, 08:00 PM
I have a 5914 and the vee is 70 deg included. maybe that helps?

Well, I can tell you it is not 90 degrees. Didn't look like 60 either.

Clutch

whitis
01-30-2010, 08:52 PM
Angle blocks are a good method, if you have a set.

If you have a combination square set (http://www.shars.com/products/view/2280/12quot_Combination_Square_Sets) with protractor, you can raise it up on 123 blocks and parallels so you have room to swing the protractor head. Accurate to maybe 1 degree.

If you have a universal bevel protractor (http://www.shars.com/products/view/2322/320_Degree_Universal_Bevel_Protractor)
you can measure angels to about 2 minutes of arc precision.

If you have a digital level, you can measure the angle of the bed then measure the angle of the V and subtract. Good to maybe 0.2 degrees.

If you have two different size precision steel rods of known diameter, clamp a good 123 block or other square next to the V. Drop one rod in, measure the distance to the top of a 123 block using the depth rod on your digital caliper or other instrument. Replace with the other rod and measure again.
Difference in rod diameter over difference in height is the rise over run of the taper.

If you have a gear tooth caliper (http://fractioni.com/inc/sdetail/1691) you can measure the profile of the V.

If you have gage blocks, you can stack them in creative ways to measure rise over run. If you also have a good square and a sine bar, you can use the gage blocks with the sine bar to measure angle.

If you clamp two parallels together at an angle, you can reproduce the angle
of the V and then measure by proxy with instruments that are clumbsy near the bed.

Be aware of what you are referencing the measurements to. If your carriage, etc., rides on two sides of the V and one distant flat surface the adjacent flat surface may not be the best reference.

Avoid the very bottom and top of the V where it may not be flat (radius, camfer, undercut, etc.) and avoid worn sections of the bed. It is possible your V is tilted a bit.

Cameras and flat bed scanners can be used to measure things, but there are perspective and distortion issues. Paper, clay, wax, low melting point alloys, alginate, plaster, etc. can transfer dimensions to the scanner, if you are careful. Or use a piece of soft material, a file and/or scraper, and some dye to fit a mating part. Or an existing carriage, tailstock, steady rest, etc. that fits well can be measured on the scanner. Either put the part on the scanner or vice versa. imagej (http://rsbweb.nih.gov/ij/) or IMAL (http://brneurosci.org/tnimage.html) (formerly tnimage) can be used to measure if you have an undistorted image.

However you measure, don't expect a part made to those dimensions to fit exactly. It may need a little fine tuning.

Boucher
01-30-2010, 09:52 PM
This is for a clamp for a indicator. You guys are making this way too hard. A graphical solution is accurate enough. If you think it is 70° cut a notch in something and try it. This doesen't call for ringing precision blocks together or measuring to four decimal places.

Rich Carlstedt
01-30-2010, 10:09 PM
I have a 6300 Clausing 200
The angle as measured with a precision vernier protractor on the dovetail is 90 degrees.
the bed was rescraped by the previous owner, but I doubt he changed the angle.
Rich