[rdsi]

The parts probably look something like this after the lathe OP.



My first thought is that you might be able to get away with screwing them into a fixture plate. The parts will cinch-up against the mating surfaces & if your CAM program makes all it’s cuts such that the forces are all clockwise that might be enough that they stay put. Otherwise, the plate would need some more features – not too difficult…

Yeah, I see your OD is 29mm and that’s not going to happen with a 5C collet & bar puller. I think the max here is 1 1/6” or about 27mm. With the 3-jaw chuck on my Slant-Pro I can get 1.5” through the spindle. Unless you can make your part a little smaller OD wise you would have to use the 3-jaw chuck and advance the bar stock by hand – at least on the Slant-Pro. There are machines with hydraulic chucks but they’re pretty expensive.

I’m not a fan of the Rapid Turn concept. Just too much work to switch back & forth.

I think it’s doable and that’s why I have a few machines. It’s costly to make prototypes and small lots and that’s where these hobby machines come into play. I’m retired (don’t have to work anymore) but I still like making things.

[motoeng]

Yep - that's exactly what the blank looks like. For what it is, I think the concept of the Rapid Turn is great for those who don't have the funds or space for a second machine.

The setup/breakdown would not be bothersome to me. I've been anodizing my own parts for years and due to lack of space, I don't have a permanent anodizing line setup, so it's an hour for setup and a little less for breakdown each time I run a batch of parts. Horribly inefficient, but it's what I have to do to get the results I'm after.

Would you happen to know how much material would need to be held inside the chuck in order to machine this part, or are there specs somewhere that tell you this? I'm wondering how much waste I would have when turning each one.

[cncoperator]

Would you happen to know how much material would need to be held inside the chuck in order to machine this part, or are there specs somewhere that tell you this? I'm wondering how much waste I would have when turning each one.

There are never ending machining strategies. If speed and thread concentricity to the other features took a back seat to conserving material you could cut threads in the first op and then screw the part into a fixture and do all the other turning ops which would result in minimal material waste

[kstrauss]

You could use blanks long enough for two parts, thread both ends and then saw/part the threaded pieces into two parts for the next operation. That approach would probably eliminate any wasted stock for clamping.

[motoeng]

You could use blanks long enough for two parts, thread both ends and then saw/part the threaded pieces into two parts for the next operation. That approach would probably eliminate any wasted stock for clamping.

Not quite sure I follow how this would work.? Are you saying you would turn the entire outer profile (threads included) but stop just short of cutting it off, then flip the blank in the chuck, and turn the other end? That doesn't seem like it would work since the chuck wouldn't have very good contact area with the newly turned end, so I must not be understanding correctly.

[kstrauss]

Not quite sure I follow how this would work.? Are you saying you would turn the entire outer profile (threads included) but stop just short of cutting it off, then flip the blank in the chuck, and turn the other end? That doesn't seem like it would work since the chuck wouldn't have very good contact area with the newly turned end, so I must not be understanding correctly.

I was unclear.

Turn or mill + thread mill the end with the threads including the shoulder adjacent to the threads. Flip end-for-end and repeat for the other end. This will give pieces with threads on both ends and the middle section completely un-machined. Slice in the middle of each piece. Screw the resultant pieces into a fixture so that the not yet machined ends are up and mill as a batch. You'll need a slightly fancy fixture that locks the screwed part in place to prevent unscrewing or use LH cutters as Ray suggested. I'm assuming that having the two ends concentric is also a +/-0.005 tolerance.

If thread milling gives an adequate surface finish your could do everything on the mill and have very little wasted stock and by doing in batches greatly reduce the number of tool changes.

[brian257]

Don't forget about the option of getting your turned blanks from another shop and then buying a Tormach to finish the milling parts of it. Not sure how much you would save getting the parts with just the turning done vs. having them completely done, but might be worth looking into. That option might be particularly appealing if the different designs you want to be able to make can all start with the same turned blank. You will also then have a machine that you can use to completely make your prototypes, short run production, custom engraving on your parts, fixtures, personal stuff you want that have nothing to do with your business and whatever else you need even if it doesn't work out as your main production machine. If nothing else, you will learn a lot and have a machine that could be resold if you decide you don't need it. Find a good deal on a used machine and your risk is very little.

[SCzEngrgGroup]

My first thought is that you might be able to get away with screwing them into a fixture plate. The parts will cinch-up against the mating surfaces & if your CAM program makes all it’s cuts such that the forces are all clockwise that might be enough that they stay put. Otherwise, the plate would need some more features – not too difficult…

It has little or nothing to do with the CAM. It would require CCW-turning (i.e. - "left-handed") tools.

Regards,
Ray L.

[rdsi]

It has little or nothing to do with the CAM. It would require CCW-turning (i.e. - "left-handed") tools.

Yep, you're right about that ...

Another thought was using some air pressure and adding some dowel pins in the threaded holes to better align things. Something like this could be held to perform the top ops then rotate 90 degrees to drill the two little holes.