Dividing plates

[rock_breaker]

I have a 40:1 worm gear that I am trying to re-purpose to a dividing head. I am to a point in planning for the dividing plates that I will try making myself, however I would like to mount commercial plates if my plan fails. At this point I have no idea of the spacing of the mounting screws for these plates, nor the diameter of the center hole.

If I knew the distance between two of the mounting holes I believe I can make a bracket that will accept commercial plates. The intended O D of the plates 6 inches.

I would certainly appreciate it if some one would take the time and effort to measure the c-c of the mounting holes and the hole size on their plates and advise me of the measurement also the brand of plate if available.

Thanks,

Ray (Rock_breaker)

 

[Uglydog]

DH plates come in a variety of outside diameters, and inside diameters.
Really depends on the manufacture of the DH.
I think I have 3 different DH. The plates are not inter-changeable.
Sorry.

Daryl
MN

 

[Bob Korves]

Even plates that are the same diameter are often much different. They often have three countersunk screws holding them to the DH. Trouble is, the screws can be different sizes, on different bolt circles, and can have different size center holes. And, they can be off by just enough that an eBay set won't fit. All of that is important because they are usually hardened, difficult to hold for machining them, and must be accurate for the pin to engage around the circle. I think the best plan is to have them made by someone with a CNC milling machine...

 

[TORQUIN]

I made plates for my Ellis 6" dividing head on a rotary table. They came out great. Mounting for this dividing head is 3 holes x .250", countersunk, on a 1.625" circle, with 1.125" center hole, but as said before different manufacturers have different mounting patterns.

Chris

 

[Bob Korves]

I made plates for my Ellis 6" dividing head on a rotary table. They came out great. Mounting for this dividing head is 3 holes x .250", countersunk, on a 1.625" circle, with 1.125" center hole, but as said before different manufacturers have different mounting patterns.

Chris

My hat is off to you, Chris. Drilling that many holes on multiple bolt circles while (I assume) setting the angles by dial and doing the math for each one is not a trivial project, and very easy to make a mistake. I would likely put the last hole in the wrong place...

 

[rock_breaker]

Thanks Chris,
You have supplied the very information I need to continue with my project.

A word about my 40:1 worm gear, it came from a cement manufacturing plant; has a 7/8" output shaft mounted on tapered bearings and is totally enclosed with no sign of wear. I am not sure how you indexed your dividing plates, but I am following Mr. David J. Gingery's method as out lined in his book "The Dividing Head & Deluxe Accessories" . One exception is that I have a drafting program that will divide a circle into any number of segments. Printing such circles and taping them on my index plates will hopefully help in maintaining accuracy.

It seems there are as many manufacturers of dividing heads as there are machinists, and at this time my budget makes me lean to the DIY method.

Thanks guys!

Ray

 

[Bob Korves]

Thanks Chris,
You have supplied the very information I need to continue with my project.

A word about my 40:1 worm gear, it came from a cement manufacturing plant; has a 7/8" output shaft mounted on tapered bearings and is totally enclosed with no sign of wear. I am not sure how you indexed your dividing plates, but I am following Mr. David J. Gingery's method as out lined in his book "The Dividing Head & Deluxe Accessories" . One exception is that I have a drafting program that will divide a circle into any number of segments. Printing such circles and taping them on my index plates will hopefully help in maintaining accuracy.

It seems there are as many manufacturers of dividing heads as there are machinists, and at this time my budget makes me lean to the DIY method.

Thanks guys!

Ray

Another thing you can do is to just cut a few blanks out of aluminum, make the mounting holes, and then just drill hole circles _as you need them_. How many of us here have used even 20% of the holes on our dividing plates? Aluminum is fine unless your project has LOTS of indexing. They do not need to be pretty, they just need to do the job at hand...

 

[DaveInMi]

I made the Gingery dividing head. He writes that the error is reduced by using the outside edge of the plate for layout. I used a cad program to make my measuring tape and printed "1 to 1" scale. I worked fine. I think it will turn out better than you may expect.

 

[coffmajt]

I recently made a new plate for my rotary table which can also be used as a dividing head due to needing to make 37 tooth and 47 tooth gears for my South Bend lathe. I was lucky because the DRO on my mill has a program to do circular bolt circles so drilling all the little holes was simple. Like others have said, fitting the three countersunk bolt holes actually turned out to be harder. Good luck Jack

 

[TORQUIN]

I made an Excel spreadsheet with the calculations, having the number of division (holes), then what that translated to in degrees, then number of turns on my rotary table + degrees (minutes) after the whole turns. I did screw up one plate, as I got confused as to which circle I was working on and did one twice.


Of course it doesn't have the most beautiful surface finish, but I won't tell anyone.

Chris