[JBV]

Naaa no spindle break When you use the 4th axis continuously you can't use a break anyway! Feel like more cnc without it! The only reason i model the stepper with double shafts is that i already have bought 6 of them hehe

The shaft is a 35mm OD tube with 5 mm thick walls. The bearings is 54mm apart. and 14mm wide. Hoped that would be rigid enough! Perhaps i should try to do some analysis

[JBV]

Yeah i have been thinking of backlash adjustment.. But i don't like the idea of the eccentric shaft thing. If the gears don't line up perfectly you would probably get uneven wear!? And i don't want the motor mount to be "loose".

Perhaps it would work with springs that push the worm axle up into the gear in some way?

[JBV]

Made a quick 2D drawing test of the axle... It was a long time since i did 2D so the layout and dimension positioning sucks And i forgot to annotate the threading and tolerances :P

[JBV]

Here you have the first drawings!

[RotarySMP]

Excellent models, and drawings.

It seems to me that you need a pretty decent sized lathe and mill and a rotary table (or CNC mill) to be able to manufacturer it though.

What advantage does this approach offer over buying a chinese 6" rotary table and making a motor mount? The steel required will probably be close to the price of the chinese rotary table.

I have made pleanty of parts for my lathe that are available, but I didn't want to shell out the money, but this only works if the material costs are low.

Another option for the back lash is to make two worm wheels, mill half thickness off each one, place them together and spring load them to oppose each other.

[JBV]

I think you can make most of the parts in a 3 axis cnc mill with ~160mm y axis, except for the axle and threading of the front plate (if you don't have a threadmill ) I plan to cast the housing and bearing retainer plate of scrap aluminium, so the those parts will not cost me anything

Well the reason i'm getting into cnc is that i want to design and build things How fun is it to just make a motor mount?

[RotarySMP]

Now that is an argument I can relate to. Making parts for machines so that you are capable of making more parts is fine ambition.

It is fun to design thinks that can be built entirely on a a more simple machine though.

[JBV]

I will build a screwless center vise and a 4 jaw independent chuck with a matching trough hole for the rotary table too

[RotarySMP]

Are you drawing in Catia?

[stormelf]

i think that he works with solidworks

[JBV]

Yep... Can't live without it

[RotarySMP]

What materials are you assigning for on those parts you posted? I fine the standard metals in the catalog far too reflective.

[JBV]

Well, the housing and bearing support is Aluminium 1060 alloy.
The front plate is Cast alloy steel.
The axle is AISI 1020.
The bearing covers, screws and stepper mount is Chrome stainless steel.

I actually intend to build a small induction vacuum furnace so i can just buy scrap metal cheap and remelt without reactions and contamination Have lots of projects i want to try out and i don't want to buy unnecessary expensive materials

[Pat2000]

I completely agree ! :cheers: I wonder what the 359 tooth one was for LOL but don't worry you don't have to explain, my guess is to match some slow speed motor?

I was one of those telescope making guys, years ago. I tried the hobbing with a tap, but wasn't overly pleased with what I ended up with. You are correct, a large tooth number with a fine pitch tooth is going to average out a lot better than a small gear with only a few teeth, for the reasons I described.

Amateur astronomers taking astrophotos fully expect to sit at the guidescope and make fine adjustments to keep a star centered on a crosshair. So if their large gear is plus or minus a tooth or two, it really doesn't matter to them. Inherent inaccuracy of the gear is discounted by too many other factors, like the aberration of starlight and atmospheric refraction, so even a perfect gear still needs to be actively tweaked to keep the scope on track.

For a rotary table though, a person is going to want a fairly strong tooth, and this precludes cutting the thing with a thread tap. And most certainly, he will want a common 40, 60 or 90 to one tooth ratio, not a tooth more or less. And he would like the gap to be the same between all the teeth without a catchup glitch between #40 and #1

I built the first rotary table that I ever owned, using a standard Browning worm and gear. I had enough fun building all the rest of the table, I was quite happy with the results, using the commercially made gear.

[Pat2000]

You might also consider some kind of large diameter bearing beneath the outer diameter of the table platter. It could be a plain bearing or an anti-friction type, even a track filled with loose steel balls or something. This is because the torque of milling some distance from the rotary table can apply a lot of torque to the platter, and you are currently counting on a lot of support from the threaded on connection, on a relatively slim spindle.

I'll second that, reckon the bearings want to be on the outside.

[JBV]

Worst drawing ever! I just finished the housing drawing... Don't stare at it to long, you might go blind!

[aubrey]

Hehe Back to the origional question then: Can i modify it from A to B without making it eccentric of the axle?

I take it that the gear is hard so the easiest (and possibly most expensive ) way to accurately do the mod is with a Spark Eroder. Maybe a "tame" tool and die making company in your area could give you a quote.

[GAWnCA]

I guess i just have to try when i get the mill converted

This is the gear i have in mind http://www.kuggteknik.se/lager2.htm
Perhaps i should ask for a quote for a custom gear... They seem to have good prices!

Too bad it's in a language I can't read.

[Dfennell]

Here's another way to gash the teeth, without the use of a rotary table to start with...

Pretty neat and workable idea, although I don't think it would be necessary to do the 2 sets of holes on the front and rear of the blank; just one set straight through would work fine.

http://webpages.charter.net/mbonfire/wormgear.htm

[GAWnCA]

Here's another way to gash the teeth, without the use of a rotary table to start with...

Pretty neat and workable idea, although I don't think it would be necessary to do the 2 sets of holes on the front and rear of the blank; just one set straight through would work fine.

http://webpages.charter.net/mbonfire/wormgear.htm

Looks cool and I think you are right about the holes, since they go away at the end of the process. Do you know of a supplier where one can just buy a set? And what would you think the tooth ratio should be?