# Rate of taper on bridgeport gibs?



## LEEQ (Apr 2, 2014)

Hopefully that's a bit clearer than mud. I'm hoping somebody knows the rate of taper on a gib strip. I'm also curious as to what else is tapered. Assuming we are working with the x axis (table).  It makes sense to me that the way on the saddle that mates with the gib would be tapered, as well as that side of the gib. Am I on the right track? Or am I ass backwards and the face of the gib that mates with the table way and the table way are the tapered surface?


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## LEEQ (Apr 3, 2014)

Well I figured out the relationship of the parts, still not sure as to the rate of taper though.


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## chuckorlando (Apr 3, 2014)

What did you find?


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## LEEQ (Apr 4, 2014)

The taper on the gib mates to the taper on the part it is anchored to. The surface that the way slides against has to be square in order to maintain the same fit through the range of motion. I might have to pull a gib to measure the taper though.


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## tertiaryjim (Apr 4, 2014)

I can't answer your question but have been wondering what gibb taper they use as well.
On my cheapo china stuff the gibbs taper 13.15 mills/inch.
They fit so poorly that the measurements vary a bit.
I've pulled the gibbs on Bridgeports in the past and it was easy to do and re-instal.


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## LEEQ (Apr 4, 2014)

My most accurate means of measuring would be to use the dro. Measure in one spot by using the z or u axis, move over in the x axis say 10" and measure again. Perhaps I can remove the y axis gib and clamp the saddle to the knee somehow. Then I would have a gib to measure and two axis to measure in. Jim, how did you measure yours?


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## tertiaryjim (Apr 15, 2014)

LEEQ
Lost track of this thread. Sorry it's taken so long to answer.

I pulled the gibb and used feeler gauges to measure the actual gap.
Easy to do on the small end but I had to be careful to get a good reading on the large end.
Want that one to just start in.
Divided the variance by the length of the saddle.
Compared those measurements with the key.


I checked my notes and the actual taper averaged 0.013" on this jet machine.
Yes" averaged" because the work is so crude.
Haven't converted that to metric.
I'll make the gibb a little thick and long because I'll scrape the ways and gibb.




This is the setup for machining the top and bottom angles.
The clamps worked well but with such a little machine I had to slide  the gibb forward for the second half.
The long taper hasn't been cut in this pic but the clamps could be angled for that taper as well.


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## LEEQ (Apr 15, 2014)

So the taper measured .013 different, over what distance? I want to approximate this angle on another machine and will be making the parts, so close is good enough. Do you intend to post a documentation of your gib and way work? I'm sure lots of us are interested.


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## chuckorlando (Apr 15, 2014)

could one not just trig the triangle? Take the diff between the thin side and the tall side and that would be side opposite and you have side adjacent in the length. That should be enough to find the angle would it not?


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## LEEQ (Apr 15, 2014)

Jim has ready access to the numbers with his stuff torn apart. I need numbers to run formulae. Actually, skip the fancy math on this project.. Taper per inch is all I intend to figure. That will allow me to set up the offset and make the cut. Ie: if his tapers.013 in 10", my taper will be .0013 per inch. I'm playing with tapers not matching them, so I have a little freedom and no great need to convert to angles and such.


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## tertiaryjim (Apr 15, 2014)

OOPS! 
That's 0.013"/inch.
I'm concerned that may not match your machine as the china stuff is so random.
You should only trust the actual measurements from your machine.
Pulling and resetting the gibb is easy. Just keep it clean and I lubricate it before sliding it back in.


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## chuckorlando (Apr 15, 2014)

I follow you.


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## tertiaryjim (Apr 15, 2014)

I had a piece of stock leftover from making the clamps pictured earlyer.
It's 1-3/8" x 2" x 11.5"long so I mounted half rounds on the ends on 11" centers.
The half rounds are the same thickness but I made a spacer, Brass, to give me the taper required and when I run into a different taper I can make a new spacer.
So it works as a NON precision angle plate.
Will improve it a bit as I go. Keys and a backstop for aligning the tool to the table and keep the gibb straight.
Might true the mounting surface up a bit.
I have to use two clamps and move them as needed.




- - - Updated - - -

I have been taking some pictures but want to get well along with the work before posting it.
Some of the machine improvements I've done were before joining the site and I never made a record.

LEEQ Now I see that your making something new and can use any taper you want.


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## LEEQ (Apr 17, 2014)

.013/inch. Got it. I will do rough measures on one of mine without pulling it and see how they compare, thanks.


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## toolman_ar (May 19, 2014)

LEEQ,

Did you get your dimensions?

I have a Bridgeport Table and saddle that I have been cleaning up over the week end.

If you need measurements I would be happy to provide them.

toolman_ar


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## tertiaryjim (May 19, 2014)

Toolman
Please do let us know.
I'm just curious now but may make a tool that could use a taper gib latter.


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## LEEQ (May 19, 2014)

I did not. I decided that as my projects must follow order of importance. The tapered gib project will wait until I work the mill over. While doing so, I will measure the gibs. In the mean time, I'm very interested in the rate of taper on yours. Anything close to .013/"?


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## toolman_ar (May 22, 2014)

I just measured the table gib:

0.0119 on the fat end
0.0131 on the thin end

On the saddle:
0.015 fat end
0.012 thin end

i measured in 3 places and took an average.
There is a line where it was ground and the years have worked off about 0.002.

Hope this helps.

toolman_ar


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## toolman_ar (May 22, 2014)

Sorry about the double picture, I cannot find a way to delete the first picture.


toolman_ar


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## LEEQ (May 22, 2014)

Thank you, do you have the distance between the two places the measurements were taken?


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## toolman_ar (May 22, 2014)

Lee,

I measured in one inch from the end.

Do you have an old gib?

toolman_ar


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## LEEQ (May 22, 2014)

Gibs aren't all a certain length, and one of mine has been stretched. I'll measure mine later this year when the mill is apart and see what taper per inch they have.)


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