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Showing posts from April, 2014

Step #1: Imagining the WW lathe Steady rest

After weeks of creating temporary solutions for holding longer pieces of stock and after an equal number of weeks searching online for a micro-adjustable steady rest (ebay included), I came to the conclusion that the vast majority of what was available for my beautiful little WW lathe were steady rests with much more basic functionality. Additionally, the vintage steady rests were regularly selling for astronomical numbers on Ebay. I resolved to design exactly what I wanted and make it! (Below is the completed result of what began as this wish to have something better than what was available). It is now working so well, I decided to do more than post the fun of making it. I'll be offering the main parts as a kit for anyone who is interested and I'll do my best in this blog to detail all the specific process insights I learned while making this wonderful tool .
It is now working so well, I decided to do more than post the fun of making it. I'll be offering the main parts o…

Step #2: Designing and Modeling the Steady Rest

I have a lot of experience in going from concept to prototype as I am inventor with an industrial design degree and am fully trained in drafting and modeling my designs in a 3D program, and have had many of them rapid prototyped using today's cutting edge services available online.
I had also been experimenting with making parts from bronze infused stainless steel from shapeways rapid prototyping service and had been extremely impressed with how detailed, dimensionally accurate and functionally strong the parts made from this material and process were.

Diving in, I developed a micro-adjuster system that was low profile and could be adjusted with finger pressure yet lock down rock solid once dialed in. I also wanted the steady rest to pivot open like on the big boy lathes for the ability to perform multiple machining operations on a part and replace it into the lathe with extreme accuracy. It's also great for multiple parts in small runs.

It was also important to me to make th…

Step #3: Establishing the first surfaces on the Steady Rest frame halves

Well, Christmas in September arrived! The upper and lower parts for the frame were the first to arrive from Shapeways. As you can see, the finish resembles casting even though there is no casting involved. A big difference is that there is no differential cooling shrinkage and warping happening like you get in traditional casting. This means I didn't have to design an overly thick part to remain material safe and that in turn has huge benefits like:
All critical surfaces are very close to final dimensions and can be brought to final dimension with a file and lapping, or you can machine them as well, your choice. I used both.I am able to include very accurately located guide holes for drilling out screw and pivot locations without having to blue and scribe or spend hours doing centering and numerical set up on a mill.

The very first surface to fit are the sides of the two little alignment nibs on the top surface of the lower frame half. This can be done with an edge file (only the e…

Step #4: Lapping the front faces on the Steady Rest frame

I was careful to keep a slight interference fit on the alignment nibs in their housing slots on the top half of the frame. I can now push them together and easily hold them in place with one hand. This is important because the next step is to lap the "front" face of both parts simultaneously on a flat surface using increasingly finer grits of sandpaper from 80 grit to 600 grit. I designed the frame to work this way on both the front and back. As I lapped, I was careful to keep changing up how I held them and keep doing circles and figure 8's on the abrasive paper so as not to lap more metal off of one side and lose parallel from front to back. This didn't take more than 20 minutes to bring up a great surface that just looks terrific. I stopped at 600 until the whole unit is built because of the scratches I'll undoubtedly get from some of the other work.

Step #5: Lapping the back faces on the Steady Rest frame

Rinse and repeat for the back using a feeler gauge to keep testing that you are staying absolutely parallel to the front face. Of course, you can also use a mill to do the same now that you have a good flat front surface to set face down. As with the front, just take off enough to get to a smooth surface. I've designed it so that the front to back thickness is not critical (but parallel is key).

You'll notice I added two brass strips to the saddle surface of the bottom of the frame. You can choose not to but I've just carefully lapped a 15 inch lathe bed that took hours and hours and I want a softer metal touching it wherever I can. There's plenty of material on the raw part to tune the center height to fit any of the WW style lathes.

Step #6: Making and installing the pivot on the Steady Rest

With both faces as reference, I machined the mating pivot faces flat. You can use a mill or even your lathe by making a temporary jig to hold it vertical and positioning correctly on your cross slide. With that done, it's a simple matter to clamp the halves together and drill through the guide holes in the parts at the same time. This ensures absolute alignment. The dimensions for the pivot are included in the detailed part drawings included with the kit. You could make the pivot pin out of Air or Oil hardening steel but I found plain old mild steel works fine. Again, your choice. The screw is a stainless steel hex head cap screw 6-32 by .5 inch long. All the finger clamp screws are the same so that one Allen key adjusts everything.
I've made brass fillet washers for the pivot screw and for all the finger clamp screws as well. I like the addition of the brass with the bronze/stainless color and they spread out the stresses. You can design whatever you'd like here. I chose …

Step #7: Lapping, back-facing, drilling and tapping the steady rest finger clamps

While I was working on the frame, the finger clamps arrived. They were beautiful and equally as accurate as the frame parts. Little bits of suspension compound remained in the grooves but 2 minutes work with a scribe and they popped right out. Any of the compound that was left deeper in the holes just disintegrate when the drill comes through. It's soft stuff.
I went to work lapping the front faces to great success. So much fun to see things come along so quickly!
I lapped the face first just removing enough metal to bring up a good shine. Fun to see the "M" monogram on the parts. I then held the clamps in a chuck and centered the guide hole on the rear stem for accuracy of turning and drilling. A four jaw chuck would have worked as well. I then turned the shaft down to .225, a free fit in the cast barrels in the frame. I also faced off the back of each clamp removing about .050 in depth to the front face. You can remove more later if need be and this dimension is not cr…

Step #8: Fabricating the fingers for steady rest

I could have rapid prototyped the fingers but it's relatively easy to fabricate them from 3 pieces of 2.25 by .75 square brass bar stock and about ten times less expensive. I started by machining down the width of the bar stock pieces as a touching slip-fit into all three slots. They shouldn't rattle but they should slide easily when it's all done but that means starting just a little snug so your final clean up doesn't leave them too loose. Remember that you'll be removing a bit of material from the sides of the channels as well.

Next step is to reduce them to .375 thick from front to back so that the clamps will have a small amount of travel to clamp the fingers down tight. A few moments at the sander with the miter gauge set correctly and the matching 30 degree angles were on the tips. Leave the blanks long at the top right now as you'll trim them during a later operation.

Time for bluing, marking out of the slots at .25 wide and the correct length (detail …

Step #9: Making the hold down bolt, nut and washer for steady rest

Here's something exciting. Once you reach this point you are very close to using the steady rest. I actually had to use it to fabricate the lead screws for the fingers. In order to use it I needed to jump over to fabricating the hold down bolt and the nut and washer to clamp it to the lathe bed.

The bolt is nothing more than a .25 diameter piece of stainless steel rod 2.25 inches long and threaded both ends with a 1/4 - 20 thread. The body is tapped correspondingly. Be sure not to drill all the way through the foot and break out the top.

The stainless steel nut is fabricated from a short piece of 7/8 diameter hex rod. This is important because there is not room beneath the bed rail to bring your cross slide in very close if you use a star knob on the steady rest. As you can see from the photo, the hex nut solution gives full clearance and is beefy, easy to manipulate, and you can crank it down with a wrench if you need to. The washer is just simple brass. I went one size number dr…

Step #10: fabricating the finger lead screws

I started with three pieces of 5/16 stainless steel hex rod 2 5/8 long. Since I wanted to turn these between centers to get good concentricity and that means centering and drilling both ends.

To use my steady rest on the hex rods, I needed to make a mild steel carrier sleeve with my lathe that was a light interference fit over the hex rod. This allowed me to use the steady rest (only finger push and mallet tap to adjust right now) to center it all up for center drilling on both ends. This was so satisfying and it worked perfectly!

I wouldn't want to stop here and just go with finger push forever though because I've seen many a steady rest with the brass fingers mushroomed from "tapping" as a way to micro-adjust. It's also just not that accurate as its easy to overshoot your goal causing you to have to reset and start over aligning the part (even more of an issue if you have a sensitive dial gauge in contact with the part while tapping).



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