Thread: Your latest project

Very Nice .RC.
I suppose it's going to be full of gear very very soon

Phil

Nice RC, that little extension of yours is getting on you half the size of my shed lol


Stuart

Originally Posted by Stustoys

Nice RC, that little extension of yours is getting on you half the size of my shed lol


Stuart

looking good R.C.
its about the same size as my shedlol

cheers
Harty

Size does not matter.... Seem work much much much more impressive then I would ever be able to do come out of small sheds....

This has been five years in the making as well..... Luckily here you do not have to worry about council rules and regulations either...

Originally Posted by .RC.

Size does not matter.... Seem work much much much more impressive then I would ever be able to do come out of small sheds...

Oh for sure, and the more space the more temptation to fill it with "useful one day" stuff.... like my shed

Stuart

It's depressing when you see extensions that are nearly as big as your entire shed!

A dust free shed? Wow that would be awesome. Even if I was to build one of those, it would end up full of crap.... and more dust!

Nice extension BTW.

I have been working on a couple of projects...... Both related. I have just finished my rotary indexer as shown here:Rotary table indexer - CNCzone.com-The Largest Machinist Community on the net!

Thanks goes to Steve Ward for his help and his thread!
Also Thanks to Joe Hovel for programming my chip (I don't have an RS232 port on my PC!) and for answering all my stupid questions!

My other project relates to the first. After machining some CI on the RT I decided to take it apart and give it a clean.... Oh and to have a look inside!

So I gave it a good clean, no biggie but I was disappointed to see no thrust bearings on the worm shaft. Only a bush at each end. The end closest to the handle had a threaded bush to adjust the preload.

In order to facilitate the adaption of my indexer, I want as least amount of backlash as possible but still minimise the drag for the stepper. Both bushes are about 9mm in thickness and the shaft is about 17mm. So I removed the bushes. The worm end of the shaft now has a standard thrust bearing (17mmx30mmx9mm), the handle end was a little tight so I had no choice but to opt for a needle roller thrust bearing (17mmx30mmx4mm). The threaded bush was machined down to allow the extra thickness of the needle bearing and was then retained to provide the preload (same as before)

Now turning the handle is smooth as silk (it was OK before) but it has no noticeable endplay and due to thrust bearings each end, machining can be done CW and CCW (user manual states only to machine in CW rotation)

The RT is now very smooth and has about 2' of backlash.

Photo1 insides of the RT indexer
Photo2 Rotary indexer, finished
Photo3 Cheapie Stepper motor driver I used. I had to remove the cover and heat sink to fit into the die cast case. The case now provides heat sinking for both the stepper controller and the 7805 regulator.
Photo4 Worm gear housed in its eccentric carrier, standard bushes fore and aft
Photo5 Worm gear with the bushes removed
Photo5 Worm gear with the new thrust bearings
Photo6 Worm gear and eccentric carrier fitted with thrust gearings and front preload bush

I still have to make the stepper mounting bracket. It will take up the 4 screw holes where the dividing plates would normally attach to. The stepper motor is a nema23 with 425 Oz.in (love those SI units!) of torque. It should do the job nicely. It'd driven by a dis-used printer power supply of 31V 2.5A.

Cheers

Simon

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Originally Posted by simonl

A dust free shed?

It has changed from dust free to in built pool at the moment..... Was planning on getting the final materials to weather proof it yesterday..

Lets just say 540mm of rain in 36 hours cancelled the trip and a bit of water got in...

540mm!!! Kinda makes you wonder why you fixed the windmill

Phil

Hi Simon,

Interesting project

The worn gear swaps from one end of the eccentric carrier to the other so I'm not sure which way around it should be.

As far as machining in both directions. While you now have thrust bearings to transfer the thrust to the eccentric carrier, how is the thrust tranfered from the eccentric carrier to the main casing? I guess it is a lot more rigid in one direction than the other?(been to long since I had mine apart)

I've just pulled apart an old printer, might have to chase up one of those controls just to have a play.


Stuart

540mm! That's crazy! I guess you soon find out if your guttering or stormwater system is lacking.....

Hi Stuart,

The rotary indexer is not what I would call an extremely complex project. I had to nut out a few things because I had zero experience with stepper motors or drivers. Bipolar, unipolar 4 wire, 5 wire 6 wire What the!?

Anyway, I have managed to get through it unscathed and the indexer is a really useable piece of kit. With a worm ratio of 90:1, the indexer chip has enough bits to configure the stepper driver to perform half steps, ie 0.9 degrees/step (full steps are 1.8 degrees) and with the 90:1 ratio, this produces 36000 steps per table revolution or a resolution of 0.01 degees (0.6 minutes of arc)

It has a menu with six functions: Jog, degrees, divisions, continuous, program (allows you to program and customise up to 9 different movement routines), 5 different programmable speeds with ramp up/down and a setup menu.

There is also provision to allow for backlash in the setup menu.


For about the same price* to build as a set of divinding plates and lots of fun to build, I think it's a ripper!


As for the RT mod. The eccentric housing is attached to the main RT body with 4 M4 screws. There is provision to reduce this endplay too but it's not a big consequence because it gets locked off with the T nut at the top before you use it. I think the setup would be equally as strong regardless of the direction of the cutting force. The instructions say only to machine in a CW direction because excessive wear will occur. I assumed they meant excessive wear on the inner bush as it's not been made to take cutting loads.


* There is at least one company that sells the Indexer as a kit (for several hundred English pounds) and it's an almost exact ripoff of the Steve Ward project. Apparently they copied his project, removed his name (His name flashes up on the LCD on startup) and now sell it as a kit. No prizes for guessing how much he makes out of it! I can't stand low life scumbags who rip off other peoples ideas for financial gain.


Cheers,


Simon

Ahh!

Stuart, I just re-read you post. You have hawk eyes. Do you know how many times I went to put that worm carrier back in the RT the wrong way around!

I finished the project and then thought I would post it here so I took it apart to take the pics. Hence the reason the bearings are already greased. I fiddled with the thing for a number of hours before deciding what to do and I'm embarrised to say how many times I put the bloody thing back together the wrong way!

The first two pics of the worm (251242, 251245) are correct! You would also have noticed that the threaded bush was already machined down in the before pics! It used to be 9mm thick.


Cheers,

Simon

Rhanks for sharing, Simon!
Could you post a pic of your completed RT setup?
I'm curious how you attached the stepper motor.

Hi Joe.

I'm yet to complete that part!


Just been looking for flexible couplings. Assume something like this is as good as any? Flexible 8 mm x 12 mm Shaft Coupling CNC Stepper Motor Coupler Encoder D 25 L 30 | eBay

As for the mounting bracket, still deciding if i need to machine it out of one piece or whether I could just weld some flat plate (pre-drill the mounting screw holes first) at each end of a piece of pipe and then face off each end flat & square?


Cheers,
Simon

My latest project is a QCTP for the C6 lathe.
Made from some lumps of steel lying around the shop, it uses a piston actuated by a hex
screw mounted within the body to clamp the toolholders to the body. A hex key is used to
tighten/release the toolholder.
The original centre post and clamp knob are used to hold the body to the compound slide.
Only a single toolholder has been made so far, but it seems to be very rigid in testing.
The dovetails were cut using a scratch made fly cutter in the mini-mill.
This cutter was made from a lump of HSS silver-soldered to a shaft piece and hand ground to
an angle that ended up about 35 degrees, and used to cut all dovetails so that the angles
match. This cutter has some limitations, one, it causes some heavy shock loads in
operation on the mini-mill due to its non-helical design, and secondly, it creates some
very evil needle like chips that I have spent hours removing from my hands...
Pictured with the cutter is a gauge plate made to allow easier cutting of future toolholder
dovetails to size. This is also handy for clamping the toolholder blanks to the mill table
for tool slot milling.
Now to make more toolholders.