Which is better for cutting small gears- rotary table or dividing head?

[HMF]

Hey Guys,

For cutting gears, which works better and easier, a rotary table or dividing head?

Thanks!

Nelson

 

[Rbeckett]

For precise pitch and spacing I prefer a rotary table with the dividing plates attatched. That will give you better accuracy and repeatability if you need to make more than one. I am currently considering adding one to my HF 5980, but have to save up since I am on a fixed income from disability. Yeah I know the 5980 is not held in much esteem, but it works well enough and is accurate as I want to be. I have added a few minor creature comforts, but no major improvements or expensive mods. It has been in my shop for almost 8 years and done everything I ever asked it to do without any drama.
Bob

 

[Tony Wells]

Better usually is not easier, and easier is usually not better. That's the case here. Gearcutting should be done on a dividing head. Well, that's not really said well. It would be easy to cut certain pitches with a rotary table with division masks, but as a general statement, too much trouble to calculate the cumulative move as opposed to the incremental. And, as Shadow said, error factor too high.

 

[Tony Wells]

Of course, Bill. I was merely limiting my reply to the scope of a typical hobby machine shop at home. After all, this is the Form Theme.

 

[Rbeckett]

Bill, Tony and everybody who has replied. You guys are so right about the cut downs on other sites. Have sorta limited my time on them cause I just aint up for the drama. Goes to the old golden rule: If ya don't have anything nice to say, keep your mouth shut. This applies to giving good honest and helpfull feedback without all the animosity.
Bob

 

[Tony Wells]

Hey guys, we're all here to have a little fun and enjoy the forum. No need or desire for drama. We can help each other, watch out or each other, and cover each others' backside when we see someone doing something maybe not so wise. All in good taste. We aim to keep this forum fun and friendly.

1200rpm,
As far as working off a template, a really careful craftsman can hit a zone about 0.002 in diameter, following a layout. A layout is only as close as the instruments used, and the eye of the craftsman. On a series of many features, I'd tend to think that a rotary table would hit closer overall. Does your table have a vernier?

Edit. 0.002, not 0.0002. I don't know anyone that good.

 

[Tony Wells]

Well, that gives you 10 degrees per rotation, and you can divide that down into 60, so your marks represent 1/6th of a degree, or 10 minutes. My thinking is that isn't good enough for gears. That depends on what kind of gears and what you are going to run with them, how much noise you can stand, etc..

 

[radfordc]

I've played around with single pointing gears using a small rotary table. The gears were crude but seemed to run OK. If I needed several gears I would make a mandrel that mounted an existing gear with the correct number of teeth and use that to index the gear blank for cutting.

 

[AR1911]

Just to be clear, rotary tables come with simple indexing, and most also have a dividing plate add-on kit.
With that kit, it's essentially the same as a dividing head.
As long as you have the right plate for your project, it's much more precise

 

[Carl_in_NH]

As AR1911 points out, many rotary tables can be obtained with a dividing plate kit; the little 4" rotab I bought years ago is one such table. I bought the dividing plate kit with it, as I didn't own a proper dividing head at the time. I made quite a few parts on it, but found the assortment of holes in the dividing plate provided to be lacking the hole counts that I wanted. This table is a bit odd, with a 72:1 turns ratio, instead of the dividing head's 'standard' of 40:1. I wanted to be able to make things like dials with 100 divisions on them.

I ended up making this 'sub-plate' back in 2007 that bolts onto the supplied dividing plate without modification - just longer mounting screws, fitting under the sector-arm attachment nut and against the surface of the standard dividing plate. The holes were put in the plate using the newly installed DRO on my mill, which had a bolt circle function I was looking to use for the first time. This 50 hole plate gave me 3600 divisions out of 360 degrees, easily allowing for 100 divisions with a 36 hole advance.