Making a steady rest

[Bill Gruby]

Tom is correct Darren. Reverse engineer the tubes. Bearing ID, OD and width first. This will bring you to the bearing holder next. Its dia. depends on the bearing. I used .250 smaller than the bearing OD. When you have that dia. you will know what you need for the tube ID. Tube should have at least a .125 wall. Length is just a matter of how far you expect it to be opened. Hope this helped?

"Billy G"

[Mayhem]

Thanks guys - I would have thought that there would be a range into which the tubes should fall and that the bearing would be chosen accordingly. This is why it pays to ask questions!

Is there any reason not to make a steady rest that uses all of its possible capacity?

[Bill Gruby]

The capacity of a steady rest is governed only by its user. The one I made for the 9X20 is extremely large for this lathe. It has to be. Make it as big as you need and add .500 to the diameter, you will never be sorry you did.

"Bill Gruby"

[Mayhem]

Thanks Bill - what I meant was is there any reason not to use the full size I have (i.e. 14" less the diameter of the bearings)?

I doubt I will ever turn anything that large but you never know. I designed it at 18" ext. diameter as that matched the swing and the made it an easy task to incorporate the base. As I had originally intended to use slotted fingers (with bearings) I made the distance between diameters 2".

Perhaps the question I should have asked is whether there is a minimum safe size for the bearing tubes?

[Bill Gruby]

Again, it's pretty much the same answer. If the lathe will hold the max dia. of the steady rest and you are at ease with the set up there is no reason not to go with it. Believe it or not. the small diameters scare me more. LOL Short answer, No there isn't.

"Billy G"

[Mayhem]

Thanks Bill - I'll endeavour to strike the balance between underdone and overkill.

[sasquatch]

Great looking steady!!

[Mayhem]

Thanks!

A friend of mine saw it and asked what it was. I told him it was a lifting lug for the lathe!

[SnailPowered]

(08-20-2012, 07:09 PM)Mayhem Wrote: Thanks!

A friend of mine saw it and asked what it was. I told him it was a lifting lug for the lathe!

That is AWESOME!!

[Mayhem]

As some of you know, I was recently in the US on business and took the opportunity to spend a few days with Ken (Pixman) in his shop. We spent the best part of 3 days making parts for the telescopic rollers for the steady rest. We started with a basic design, which I had based on the drawing posted by Bill Grubby in his steady rest post and we made some modifications.

As my milling machine isn't operational yet, I was very grateful to Ken for not only doing the milling operations (and the lessons on milling) but for trusting me to run his lathe concurrently in order to get the parts made (I'm always worried about busting tooling). Unfortunately we ran out of time to make two of the three end caps and the pins to hold the bearings. I did have to down tools to watch his mill cut the chamfers on the bearing carriers though. The Prototrack system did cause some colourful language during the programming stage but there is something mesmerising about watching a mill work under its own power.

I also need to thank wrustle, as some of the stock we used to make these parts came from stock that he had given to Ken. I would have liked to thank him in person but we simply ran out of time.

OK - here are some pics:

Here the three bearing carriers have been turned to size, the chamfers milled and the holes for the bearing pins drilled. We believe this material to be 4140. The tubes are 1.125" black iron pipe, which have been drilled out to give a 1" bore. Ignore the little L-shaped block on the right, he will make an appearance in another thread of mine...



Here you can see the 6.3" long x .203" (5.156mm) wide keyway that Ken milled into each of the bearing carriers. This will prevent them from spinning in the tubes whilst being adjusted. I still need to turn down the tips of some M6 set screws to produce a Ø5.1mm x 4mm long point to suit but this will be done later.

   

What these pictures don't show is the deepest drilling I have ever done in making the clearance hole for the M10x1.5 allthread that will provide the linear travel. These had to be done in four steps using a 0.375" drill to get to the point where the chips would no longer clear the hole and then enlarge it to the final 0.562. Once that was done, it was back in with the smaller drill to final depth and then to the finished size. This required flood coolant and provided me with the odd shower!

Here is the slot to take the 30 x 9mm bearing. Ken had to to grind down the shank on his 5/16" 3-flute solid carbide (Prototyp brand) end mill to gain the necessary clearance to mill these slots to the full 26mm required. Thankfully he has a surface grinder in his shop.

   

Whilst Ken busy with the milling operations, I was busy turning the 1.125-32 external threads on the tubes, making the knobs out of 6061-T651 aluminium and making a start on one of the 416 stainless steel screw on end caps.

   

We ran out of time to make the other two end caps but Ken will make these for me and drop them in the post. I really like this material and was able to do the 1.000 x 1.000 flat bottom hole in one operation using a Valenite CenterDex cutter. I then bored a little undersized for the internal thread and cut a relief groove at the end of the bore. Having never cut internal threads before (let alone in a blind bore), I let Ken cut these and the fit is perfect.

Yesterday I managed to get some shop time, so I welded the coupler nuts into the ends of the bearing carriers. 20mm of the hex was turned off to fit into the bore and three spot welds were all that was required.

   

Once these were done, I cut the allthread to length and positioned a stop nut (secured with LockTite) to ensure that the carriers cannot be forced back up the tubes when extended. I then turned up some nylon washers and drilled and pinned one of the knobs into position. Here is the (almost) completed one, which still requires the bearing pin to be made.

   

The next major step will be to drill the holes in the steady rest to fit these. It will require some work to build a fixture to hold it securely to allow the drilling operation and I anticipate having to incorporate some bolsters to be fabricated and welded into place prior to this. However, I have't worked this out yet, so that may change. Given the time that went into making these, I certainly don't want to screw them up by not thinking things through or rushing.

Thanks again Ken, I thoroughly enjoyed our time in your shop.