Small rotary table large project, help.

[uchytil]

So I have a 6" rotary table for my Smithy 1340. I've been looking all over the place for ideas on how to do a job that will be 7" diameter. I will be making brake backing plates from 3/4 6061 for old german motorcycles. I need to know if anyone has pictures/plans/ideas how I can do this with my table. Larger plate?

 

[Lo-Fi]

You're probably going to have to give some more details on the types of ops you're intending to do?

Regardless, your biggest battle seems to be attaching the stock to the table without holes where you don't want them.... Some kind of fixture plate might not be the worst Idea.

 

[Larry$]

No matter what size RT you have, it will always be a bit small. I've got an 8", same problem. I cast an 11" aluminum disc, put 6 Tee slots in it and bolted it on. Works but takes more time to setup. I think you could just make a fixture plate. Drill & tap for the job at hand. Maybe a universal plate that you can use on the RT, vice or mill table. I see another post beat me to the fixture plate idea.

 

[JimDawson]

I added a 12 inch dia. plate to my 6'' RT to be able to work on some 28'' round pieces. The process is in this thread. https://www.hobby-machinist.com/thr...-weighing-counting-machine.90454/#post-821478

 

[uchytil]

Thanks for the replies! I'm going to be honest and say I have no idea (yet) how to make a fixture plate. One thing is for sure. The item I plan to make has a center hole where the axle goes through. In fact the hole will be larger to accept a steel bushing. Can items be held in the center hole of the rotary table? I've never used one yet. The plan is to center drill the 3/4 aluminum 7x7 plate. then cut it 7" diameter. Next is to cut an od shape on one side that holds brake components and finally cut the remaining stock down to 3/16" with and groove that matches the wheels drum.

 

[Lo-Fi]

Holding by the centre hole is fine for drilling, not for milling. It's one of those things you'll get away with until you don't, then it's quite catastrophic!

By fixture plate, I mean some arrangement to hold or otherwise interface between the work and the table in such a way that allows access for the machining ops you want to carry out. A large flat plate with holes drilled strategically will probably do. You've picked quite a challenging project for first time with an RT, it has to be said!

When workholding on my RT I do often use the center hole, with at least two other points of clamping, moving clamps if needed for clearance. Order of operation is critical.

 

[brino]

No matter what size RT you have, it will always be a bit small.

........until you go to lift it....then it will feel too big!

-brino

 

[Lo-Fi]

Just thought I'd add that there's a piece of Ali under that steel workpiece! This works really well as long as you're careful to set your cut depths accurately.

 

[DavidR8]

The sticker on @Lo-Fi's mill.

 

[Suzuki4evr]

The sticker on @Lo-Fi's mill.