Four-Wheel Steady Rest

[joe greiner]

This is probably the final version of my four-wheel steady rest. Further improvements, if any, await my purchase of a larger lathe. This lathe, BTW, is a Harbor Freight 34706, substantially identical to the MC900, and I think both of them are clones of the Jet 1236.

For most applications, roller-blade wheels mounted on a cantilever axle (usually just a single bolt) are satisfactory. On a recent project, however, multiple mountings presented intermediate conditions of severe imbalance. I reasoned that since roller-blade bearings were designed for axles supported at both ends, such attachments would be superior for significant radial loads.

Three-wheel steady rests are sufficient to stabilise most workpieces. The minimum workpiece size is limited by the wheels contacting one another. With four wheels, the minimum workpiece diameter is theoretically larger. Nonetheless, I opted for four wheels so that a laser support could reach across the top of the frame without special offsets. (The laser support is not yet begun, though.) Also, the wheels come in sets of four, and I hate to waste anything. And regarding the minimum diameter of workpiece, I found that attaching diagonally opposed pairs of support arms on the front and back of the frame could enable a much smaller diameter, subject to flexing between the rest points.

The support arms are rectangular steel tubes. Between the axle and the body of the tube, I reduced the side width so that the sides could flex slightly to better meet the axle bearings. The tubes are secured to the frame with carriage bolts ("coach bolts" in Oz, I think). The flat bar is essentially a captive spanner engaging the bolts' square necks. I welded small bits of square bar (same size as the bolts) to short angles which do the actual clamping. Wing nuts and fender washers on the far side of the frame complete the attachment.

The "beta" version performed reasonably well. But the base for attachment to the lathe bed was only 3/16" x 1 1/2" (4.75mm x 38mm) - selected because I had some of it on hand. It wasn't quite stiff enough to prevent slight vibration. So I bought some larger steel bar (1/4" x 4" - 6.4mm x 100mm) for a new base. I cut the base narrower in the region of the arms. Attachments for the new base suggested a new frame, so I made some improvements there too. The original frame was made from dimensional timber, half-lapped at the corners, which is only 50% effective. I elected to make the new frame from single pieces of plywood. I also re-designed the positioning bevels between the upper and lower parts of the frame to eliminate the registration dowels. And for the new frame, I made all of the bevels sloping downward to reduce dust accumulation. To really, really clamp the frame to the lathe bed, I added a short piece of bed-frame angle across the bottom of the bed. I used the same size bolts (1/2 inch) as I used for the main attachment, so that I only need one size spanner. Except for the base, I harvested all of the hardware from the first version, including the over-center latches. These latches, BTW, enable connecting the upper and lower frame parts in less than 10 seconds.

The construction process follows.

Joe

[joe greiner]

Construction:

I used 3/4-inch plywood for the front and back layers of the frame. I offset the layout of the top element to allow for the saw kerfs of the alignment bevels. I used progressive cutting and assembly to maximise precision. After cutting the outside of each frame layer, I rasped and sanded the mating surfaces with the bed by "blueprinting." This was almost a wasted effort, because the bed isn't quite uniform in cross section for its entire length. Then I cut out part of the interior, to just below the bevel joins. If I'd planned the bevels better, I could have used a compound miter saw for the cuts. I used a circular saw instead, and because of my dodgy planning half of the cuts were "climbing" cuts, i.e. by drawing the saw towards myself; this was to preserve the lower portion of the frame for later attention. I armoured the bevels with a coat of CA.

I used temporary and permanent screws for glued assembly. I used filament tape to mask regions that shouldn't get any glue, and added petroleum jelly (Vaseline) as a bond breaker in critical locations. After attaching the latches and verifying the alignment, I cut out the remainder of the interior on the bandsaw. I drilled holes and recesses for attachment of the base plate and the lower angle. I embedded hex nuts in epoxy for the bottom angle attachment. After assembly, I sanded the outside of the frame with a belt sander.

I tested the performance on a piece of scrap spindle turning. I didn't dig very deep in the open end, but the wall thickness on this piece is about 1mm, and constant thickness too. A light catch knocked everything slightly loose, but I reset it without much effort. If the arms were clamped tighter, or set in grooves in the frame faces, I expect I might have done enough damage to require binning the piece.

The aluminium angle at the top of the frame is intended to provide auxiliary support for a laser arm of a hollowing system (when/if). I bought about 50 of the latches from an OEM supplier for a variety of applications. The plywood was a roadside orphan from a neighbour's renovation project. The steel tubes came from a bicycle repair rack, also a roadside orphan. The new inline skate wheels were obtained at Goodwill Industries for a substantial discount; I have a large collection of used wheels from garage sales, destined for other mechanical projects. The bed frames which donated some of the material were also roadside orphans; their metallurgy is not too well suited for highly-loaded welds, but satisfactory for this application; and cobalt drills are the only type suitable.

With the revised frame, this took a little longer than I expected. If I've omitted any info, please ask.

Joe

[Caveman]

:2tsup:Nice Joe - still on my to do list - have a set of wheels hanging around somewhere - thanks for sharing.

[wheelinround]

Joe :2tsup: and can see you have one of your :rolleyes: watsamacallits in there

Pity the kid who's scrounging round the house looking for his inline skate wheels :D

[artme]

Bloody ingenious!:o:2tsup::2tsup::2tsup:

[Rattrap]

I hate lookin like a total newb but well thats just what i am. Can u tell me how it works & what its for? lol.:2tsup:

[OGYT]

Rattrap, basically, it's like this. When you're diggin' out the inside of a piece of wood, there is tremendous forces at work on the tenon. Sometimes you need extra support. That's what it's for. The piece spins inside the wheels, and can't move enough to tear the tenon off it.
The Steady Rest is placed as far out on the piece (away from the headstock) as possible, and still do the hollowin' job.
Nice stuff, Joe. You're a glutton for punishment. :D

[Rattrap]

Thanks OGYT, i recon i got it.

[JDarvall]

Looks great Joe. Thanks for sharing all that. Giving me some ideas.

[Ad de Crom]

Joe, your four wheels steady rest looks great and very sturdy.
I'm sure this steady rest works very well, and I hope without vibrations.
I had a three weels steady rest, but I'm now doing my hollowing jobs on another way, by not using such a chuck like you have, but I developed for my hollowing work a clamping chuck for a pen of 50mm (2'').
So I glue on my blanks a pen of 50mm (2'') with a lenght of 50mm (2''), and put that in my clamping chuck.
I can work with an free overhang of 250mm (10'') without problems of vibrations. Well I have a headstock spindle of 40mm on the bearings, so my headstock spindle is a heavy spindle.
If you take a look to my website http://members.lycos.nl/adecrom you see that clamping chuck, and a picture of the chuck in use. Click on the device button.
I always found the steady rest a stand in the way thing.

Ad

[joe greiner]

Yeah, maybe I should add "masochist" to my title. But it was the only way I could've made the whatchmacallit Ray (wheelinround) mentioned. Here 'tis:
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=66558

Rattrap, to expand a bit on Al's excellent description, the objective of any steady rest is to reduce wobbling of the workpiece so you can cut it without chatter. On long spindle work, the midpoint can be so flexible as to break by whipping around. A less heroic steady rest can work there, and in the extreme, the best type for "trembleurs" is the "string steady" - basically a cat's cradle embracing the spindle. Google ["string steady"] and/or [trembleur] for some examples.

Here's another I made for long-line production at the end of a dowel:
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=57866

Another favoured type is the "bowl steady" for working the inside of large bowls. This type places two wheels opposite the working point, and prevents (or TENDS to prevent) the workpiece jumping out of the chuck. The outside of the bowl is turned first, between centres. Again, Google is your friend.

The contraption I present here is suited for deep vases or similar hollow forms. As with the bowl, the outside is first turned between centres. Then the steady rest is installed, and the tailstock is removed or slid to the end of the bed for access to the inside.

True enough, Ad. But 10 inches is pretty much the limit I've found for cantilever work. Better safe than sorry. And the steady rest can of course be moved to different locations along the workpiece.

Thanks for the comments, mates.

Joe

[Rattrap]

Thanks joe, i can picture the problem & how it'd fix. I haven't done any lathe work yet but i'm itching to, along with about 20 other projects i can't wait to build. lol.

[rsser]

Fine bit of work Joe, and thanks for putting up such a well written report.

...

AFAIK the prime purpose of a bowl steady is really to stop, or reduce, the bowl flexing as it spins, in order to get a thinner wall.

Got one underway; knock off of the Oneway. Just not sure whether ply will work in place of their metal arms.

[joe greiner]

Quite so, Ern. Before you make final cuts for your clone of the OneWay, have a squint at the AAW forums: http://www.aawforum.org/vbforum/index.php

In the Main Forum, there's a recent/current discussion about bowl steadies. It seems the wheels are offset, and can create tracking and/or wear problems. Simple fix, IIRC, is to add shims to correct.

Joe

[rsser]

Thanks for the link Joe. Will study it with interest.

My plan is to use the Stubby aux bed and banjo to mount a 1" post; then attach arms and wheels to it.

[rsser]

What are you hollowing in the frame in the first set of pics Joe?

Multi-axis box?

[hughie]

Joe,

Well done as usual. along with very clear tute. :2tsup:

[joe greiner]

What are you hollowing in the frame in the first set of pics Joe?

Multi-axis box?

Hi, Ern. That's the Icosahedron Ball in the first link of post #11. I used the first version of the steady rest frame for all of the work, as the "shakedown cruise" for the steady.

In the second set of pictures, I just grabbed a spindle remnant I had on hand for the test. It may, or may not, ever become anything serious.

Joe

[Scally]

Now I understand. I think.

I will have a few more reads and see how I can use it to rout the drum shells on the router table.

Thanks.

[Ed Reiss]

Joe...well constructed:2tsup::2tsup:

....can see where your structural engineering background came into play!

[Gil Jones]

Nice steady rest, Joe:2tsup:

[rsser]

Bit OT Joe ... having looked at the Oneway bowl steady I decided to buy just their head rather than cobble together my own. Sleeved it down to fit a toolpost to go into the aux bed/banjo.

Shimmed the inside wheel out as suggested in the AAW forum.

Yet to give it a test run.

Though I see there's a guy out there who uses two complete Oneway bowl steadies to accomplish what you've made.

Would be 'big bikkies' as we say to do that Downunder.