Bridgeport for Beginners!

hmm. Okay, I thought I did that. I'll watch it again.

Now what am I suppose to do with this big bastard? Its gotta weigh 120lbs. With the 8inch chuck on top, I might have an issue. I'm wondering do these do some kind of magic where you can mount the chuck on its side? I have a big 90 degree plate, but if I try to mount this beast sideways, my Bridgeport would tip over! I'd love to find some tech data on this ol girl.

 

There's got to be some clamping bolts or nuts to loosen to pivot that dividing head 90 degrees, some pics of under the chuck would be handy.

Edit: maybe that brown suntanned thumbwheel on the left of the indexing plate in the first photo will loosen to allow the chuck to pivot. My one has a morse taper under the removable chuck that would accept an arbor to mount the gear blanks.

 

oh good times..

 

For a 50 tooth gear on a 40:1 ratio dividing head you'll need 40/50 of a turn per tooth or 0.8 of a turn. That would be 20 holes on the 25 hole innermost set of the dividing plate.

 

I think I see how you got that... I think. I gotta play with it a bit for it stick to the brain cells.

I checked that part in the video with my 30T as a sample. So 30+2/ the diameter which is 1.576 and I get P=20.304 and he says drop the change so 20.
The second formula I did was for blank size and that was 30+2/ 20 and that is 1.6" SO I think that's close enough.. Do I take either of these numbers to the handbook?

 

You are brilliant. I see it now, it does pivot. Badass! I didnt know it did that!



I raise my white russian to you sir! Now that I know how cool this thing is, I think I'll get it cleaned up so I don't get so filthy picking it up.

 

Does this mean I'm screwed with a 35, and 28 toothed gears because none of this easily divisible?

Found this for dummies. https://www.cgtk.co.uk/metalwork/calculators/dividing

36 is a no brainer. That's 1 turn on a 40 or a division every 10degrees.

 

There's a second set of different holes on the opposite side of my particular indexing plate.

 

yeah, mine is flat on the back. I'm outta holes.

 

Looks like this is the relevant cutter for a 50 tooth (number 3: 35-54 tooth) by 20 diametral pitch by 20 degree pressure angle gear:

https://www.kbctools.com/itemdetail?auto=1&itemcode=1-204-080-3

 

Well there must be some more kicking around the workshop where you got it.... There are cheap sets on Ebay but may need hole modification to fit.

https://www.ebay.com/itm/Index-Plat...785845?hash=item2b02df5a75:g:EFcAAOSwXzdgYQeT

 

I see it now. That's why I got 20 twice! One is the pitch and the other is the pressure angle. GOT IT!
I haven't been able to get back in that shop since I brought my mill home. Now a year later, I'd be dangerous in that shop knowing what I do now!
I measured my plate and found this on fleabay. Same size as mine with a different set of numbers. I probably should pick it up. Mine is 5" diameter with 1 1/8" inner hole.

https://www.ebay.com/itm/Index-Plat...868358?hash=item3b51a57506:g:bbcAAOSwhZFfqIqs

 

It's possible to make your own custom index plates using the dividing head itself, I've seen one for the gemstone faceting industry to make the index wheels for cutting stones: 64, 72, 80 & 96 tooth wheels.

Here's a full set of 5" x 1.125" plates:
https://www.ebay.com/itm/DIVIDING-H...844723?hash=item3b55666673:g:IKkAAOSwWtFgAi~l

While I think of it, you can use a slitting saw to cut full depth slots into the gear blank to minimize material removal by the gear cutter to extend it's life a bit.

 

I checked out that set. I think they screwed up and it's just 3 plates x2. They have 15,16,17,18,19,20,21,23,27,29,31,33,37,39,41,43,47,49.
That's a good idea using a cheap slitting saw to hog out most of it. I did see some carbide indexable gear cutters online. I bet those aren't cheap!

 

OMG! What the Fk chuck? Even someone like me knows what this 8inch chuck cost!

 

Those three nuts round the back of the dividing head may be for heavy duty locking of the diving head and need loosening too.

 

If you prefer a diy solution you can make a "straight" involute cutter. The involute form is an trapezoid for a straight tooth rack, and by using multiple annular cutters you will end up with a rough linear interpolation. Multiple cuts per tooth will improve the shape, especially for smaller gears.

 

Brother you are speaking GREEK to me! I'm sure what you are suggesting would work perfect, but I couldnt identify a trapezoid from a trapeze. I still suck at grinding a simple cutter for my lathe.

 

So the nasty task of cleaning this thing up starts. I backed off the big ass nuts, turned the one thumbscrew out and it didn't want to pivot. There are 2 small bolts on one side and another thunb wheel that isn't budging yet. I'd kill for a manual on this. All I've found is a guy willing to email a sales brochure. I guess I'll try him.

The chuck is off and the parts are in the bath. The scroll and the gear didn't have any rust so it's not swimming. Found a broken bolt so I'll have to remove that out of the plate. Speaking of the plate, there is nothing under there for taking it off the dividing head. Looking down the center, it looks like it's threaded onto the shaft.




Down the hole. I'd like to take it off it's not too much ass pain. I could give it a good clean this way.