Group Project: Dividing Head - Organization and Design

[Flyinfool]

Woohoo! This is gettin' real, y'all!

I've got a few questions.

1) The Auxiliary Base has two .089 holes. I assumed they would be for locating pins, but didn't see corresponding holes in the Main Base. What's up with that?

2) The slots for the locating blocks on the bottom of the Main Base. Any reason they can't run the length of the base?

3) The hole for the Trunnion on the Main and Auxiliary Bases would need to be at the exact same height. The numbers on the drawing aren't adding up. I assumed I would clamp the bases together for final boring of the trunnion hole, using the bottom to level set them.

1) The two .089 holes are for locators for pins to be installed at assembly. It will take some messing around to get the trunion exactly lined up and at that time the owner of that Dividing Head can drill and pin it to make alignment perfect if it is ever taken apart for cleaning. These will allow for either an .093 or .125 pin. I made the screw holes with some extra clearance to allow for adjustment. There are just 2 many dimensions between to realistically have them just line up.

2) No reason they can not run the length and width of the base

3) I made the Aux base short on the bottom to be sure that it will not protrude below the bottom of the base and cause a tilt when set on the table. If you are making both parts and can line bor both holes then you could screw and pin the 2 parts together before boring. I was not sure if you could bore 6 inches deep.

There will be some parts that are designed and toleranced expecting that 2 different people will be making them, IF the same person is making both parts the tolerances can be opened up a lot and that one perrson can just make them to fit together. This is part of what I will be talking to each of you on once I get the first pass of the drawings done.

 

[ttabbal]

OK, Here are the drawings so far. These are NOT finished drawings. Do NOT try to make parts from them. Critical dimensions are still being adjusted and missing info has yet to be added. These are for reference only. There are some parts of the project that I have plans for changes to.

Looking good!

On the Trunion, I could do the holes on the end with a rotary table, but it calls out a 5 degree taper. The dimensions look close to a #2 taper pin, but the angle is wrong, those are more like 0.6 degrees. 1/4" per 12" from mcMaster. Any idea where to get a 5 degree taper reamer? I see some for guitar makers, but those are made for wood. It looks like tapered end mills are a possibility...

I don't have the ability to engrave the text though. Does someone have a CNC rotary axis to do that bit? I might be able to get some cermark or similar and laser it on, but it wouldn't be as durable as an engraved marking. I'm not sure my laser rotary setup is precise enough though.

 

[Flyinfool]

Those tapered holes were based on a 3/16 x 5° per side center cutting tapered end mill. I chose 5° because it was the lowest cost tapered end mill from McMaster Carr. If I weere doing it I would predrill most of the hole and then just finish the taper and bottom with the end mill.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

The pin that drops into the hole will a part that someone here will make so it can be any angle.

The text does not necessarily need to be engraved on the trunion, it could be stamped. For accuracy It would be nice to have the lines engraved. In reality, those lines are only good as a reference for something that is not a critical angle, If your angle is critical you would want to indicate it in anyhow.

 

[ttabbal]

Cool. That sounds like it would work. I'm looking forward to seeing things progress.

 

[Flyinfool]

The engraving of the lines could be done with your smallest end mill.
Just use the corner of the end mill with it set 45° off axes to make a 90° V notch for the line. The smaller the end mill the less the run out at the end of the line.

Did this make sense? I can picture it in my head but not sure how to put it in words.

 

[Flyinfool]

Update on the drawings so far. These are NOT finished drawings. Do NOT try to make parts from them. Critical dimensions are still being adjusted and missing info has yet to be added. These are for reference only. There are some parts of the project that I have plans for changes to.
I did not update the step file as the changes made so far are of the a couple thou here and there as I am adjusting fits and tolerances.

 

[Shotgun]

Loving it.

For the Auxiliary Base, the top is a 1.5" radius, while the Trunnion hole is 2.75" diameter. That leaves a 1/4"x1/8" strip to hold the Trunnion and stop if from vibrating. Am I wrong to think this is a mite delicate? From the STEP model, it looks like there is room to make it thicker. Advisable?

That large, outside, partial radius is going to be the most difficult part for me, and the part I'm most interested in completing successfully.

The Spindle Lock and the Worm Mount are called out as .750". That is the nominal thickness of the material I'm getting and doesn't allow any room to clean it up. I don't think it will matter if they are slightly under, and .730" will allow me face off up to .010" from each side. Could we change this dimension to .74" without causing problems? (so that the allowable will be between .750" and .730".)

I just got another treadmill to rob the motor from. I think I'm going to use part of the walking platform and the current drawings to start working out my order of operations. I got all the parts for my uncle's shop press made, and I'm taking it to him Sunday. I'll be bringing back a large supply of 3/4" structural steel.

 

[Flyinfool]

@Shotgun, Its all your fault........
I made the top of the Aux Base thicker and somehow it corrupted the drawing So now I get to redraw.......

I could add some more difficult challenges if you want me to.

I have not looked at the thickness changes yet, I am still recovering from the 1st change......

 

[Shotgun]

:-(
Just remember that these computers were DESIGNED to make our lives easier.
And one new challenge per project is quite enough.

 

[Flyinfool]

OK I got the blown up drawings fixed, all the requested changes implemented, and even got a few more drawings done.
If there is anything that looks like it may cause you dificulty on the parts you are making, let me know ASAP so we can work it out.

I'm getting close, only 5 more part drawing to draw, and 4 assembly drawings to do.

Update on the drawings so far. These are NOT finished drawings. Do NOT try to make parts from them. Critical dimensions are still being adjusted and missing info has yet to be added. These are for reference only. There are some parts of the project that I have plans for changes to.