Made a hollower & need wall thckness gauge input

[Raul McCai]

My hollowing system

EDIT:

I already started a thread on the the topic of a laser and you guys politely responded ( thanks) so I edited out the Qs on lasers
I thought I that I had deleted that post before posting it. OOPS, an elder moment. .



I've built an articulated hollowing system of knuckles with tapered roller bearings.
I have left the design of the wall thickness gauging device to the last.

This is the gizmo I've built (haven't used it yet - looking forward to it though)
https://www.youtube.com/watch?v=c846eBoYKRs
various pics of the build here
http://s1002.photobucket.com/user/z...rticulated Arm Hollowing System?sort=3&page=1

 

[Hu Lowery]

looks like a beast!

Looks like a beast!(and I mean that in a good way)

I like it. Should be very stiff while having excellent freedom of movement.

Hu

 

[Larry Komroff]

Nice work. I am really impressed.

 

[Raul McCai]

Thanks guys. The diameter of the knuckles was dictated by the tapered roller bearings. I got 'em dirtier than dirt cheap; couple of dollars apiece. They were designed to replace the pedestal bearings in a Ferris Lawn mower. I don't think I'll ever load 'em to factory spec'.

My welds are horrible looking, but have good penetration. I'll do something to clean them up for paint. Grinding & silver solder or just bondo.

Now, I gotta design some tooling for it.

 

[Odie]

Looks like a beast!(and I mean that in a good way)

I like it. Should be very stiff while having excellent freedom of movement.

Hu

My very thought, as well......some serious thought and engineering went into that! 😀
ko

 

[Odie]

Don't know what your ideas/needs are about a thickness gauge, but thought I'd suggest looking into a Tompkins Gage'T thickness gauge. I don't do hollow forms, so someone else might be better experienced to tell you how applicable it would be for them. I'm betting that for some hollow forms, it might be very useful.

You see it hanging on my wall in the pic......

With the exception of salad bowls, nearly every one of my bowls are between 1/8" to 1/4" wall thickness......so, I've grown accustomed to using the Gage'T for just about every bowl I produce.......

There is a video of the Gage'T at this link:

https://www.woodturnerscatalog.com/p/87/3730/Tompkins-Gage'T-Thickness-Gauge?term=wall thickness

ko

 

[Bill Boehme]

... You see it hanging on my wall in the pic......

I am getting ready to order a few things that I need and that tool has been at the back of my mind for a while.
I have a couple Sorby tools for measuring thickness -- one is a large number 8 and the other is a large letter P, but there are quite a few situations where they don't fit very well. I know that I can do other things to check wall thickness, but the Tompkins Gage'T sure does seem to be convenient. I will deny it to the bitter end, but some say that I have tendencies towards being a gadget junkie. Bunk ... No way. Everything that I have are critical useful tools!

BTW, some guy named Kelly in Montana gave it a positive review on the Craft Supplies site and I gave a like. This doesn't mean that I will buy one ... just because I have a gift certificate is irrelevant ... I think. Let's see what other critical supplies I need. Maybe, I'll put it on my wish list ... Oops! Did I just mistakenly add it to my shopping cart? How did that happen? 😛

Odie ... looking at the picture of your shop, everything critical to woodturning seems to be right there ... except ... I think that a swivel head Vic might fit nicely in the spot where that old Woodfast is sitting. 🙄 Roof repair, you say? You don't need no steenkin' new roof if it's not raining! 😀 (Or ... one of these would be nice)

 

[Steve Worcester]

EDIT:

I already started a thread on the the topic of a laser and you guys politely responded ( thanks) so I edited out the Qs on lasers
I thought I that I had deleted that post before posting it. OOPS, an elder moment. .



I've built an articulated hollowing system of knuckles with tapered roller bearings.
I have left the design of the wall thickness gauging device to the last.

This is the gizmo I've built (haven't used it yet - looking forward to it though)
https://www.youtube.com/watch?v=c846eBoYKRs
various pics of the build here
http://s1002.photobucket.com/user/z...rticulated Arm Hollowing System?sort=3&page=1

thats some serious machining, I like it. But it is sort of a copy of something already out there.
How difficult is it to adjust the height? It looks like the bottom "puck" has a rod and grub screw. What is the diameter of the rod?

 

[Odie]

I am getting ready to order a few things that I need and that tool has been at the back of my mind for a while.
I have a couple Sorby tools for measuring thickness -- one is a large number 8 and the other is a large letter P, but there are quite a few situations where they don't fit very well. I know that I can do other things to check wall thickness, but the Tompkins Gage'T sure does seem to be convenient. I will deny it to the bitter end, but some say that I have tendencies towards being a gadget junkie. Bunk ... No way. Everything that I have are critical useful tools!

BTW, some guy named Kelly in Montana gave it a positive review on the Craft Supplies site and I gave a like. This doesn't mean that I will buy one ... just because I have a gift certificate is irrelevant ... I think. Let's see what other critical supplies I need. Maybe, I'll put it on my wish list ... Oops! Did I just mistakenly add it to my shopping cart? How did that happen? 😛

Odie ... looking at the picture of your shop, everything critical to woodturning seems to be right there ... except ... I think that a swivel head Vic might fit nicely in the spot where that old Woodfast is sitting. 🙄 Roof repair, you say? You don't need no steenkin' new roof if it's not raining! 😀 (Or ... one of these would be nice)

Heh,heh,heh.....Yeah, that was me that gave that review for the Gage'T, Bill....! 😛

If you remember.....It was right here on the AAW forums where I made the decision to buy the Gage'T......took a little coaxing from some of the other members, but I'm sure glad I bought it now! I use it regularly.

If you decide to get one, don't get rid of your other calipers.....you'll still need those, too. The Gage'T can do most all of bowl thickness measurements, but there are times when I still use the old calipers. The Gage'T is a real convenience item that will come in handy over and over again.....it's main advantage is checking up on your overall wall thickness toward the end, or over a specific area of the wall. For a single point, the old calipers still are the best for that. It's great that you can slide the polished brass balls along a 600gt sanded surface and not leave a trace that you've been there. When you do that, you're actually taking an infinite number of measurements along the track of where the balls have been.

Yes......I'd love to have a Vicmarc VL240, or in a pinch, I could use the Robust American Beauty! Ha! I'm just kidding......I think the AB is a premier lathe, but the VL240 probably suits my needs, desires, and style a bit better. The roof is done now, and money is tight again. I have no problems with keeping the ol' Woodfast......for now!

ko

 

[Raul McCai]

thats some serious machining, I like it.

Thanks

But it is sort of a copy of something already out there.

Yes and no.
The KOBRA uses 4 knuckles sort of like mine, but is smaller and lighter and does not use tapered roller bearings. So if you get any slop with use and age, your are stuck with it. I can increase the torque on my bearings.
That means there is no slop - ever.

On each knuckle: The 3/8-16 thru-bolt that connects the end caps is locked in place by a little 3/8-16 set screw, from the opposite end; exactly like a jam nut. I can loosen that set screw, apply a spanner wrench to the cap on the bottom, and an Allan wrench on the top and tighten it to the torque I please. There is no slop, none. Tapered roller bearings expand outward in diameter as torque is applied making them grip the sidewalls of the bore as well as the base of the bore and cap. That's why there is a torque specification on them when installing vehicle wheel bearings. They slip in, you squeeze 'em, and they expand (depending on diameter some can expand several tenths of a thousandth) to fill the space. Tapered Roller Bearings consume more energy to rotate than do regular ball bearings but they are immensely stiffer axially.

I considered getting a Kobra. I've read that it's well north of a Grand $ with a very long waiting list. But when I sent the guy an email, I didn't get a reply (maybe he's busy?), so I designed and made my own.

How difficult is it to adjust the height? It looks like the bottom "puck" has a rod and grub screw. What is the diameter of the rod?

The base has two 3/8-16 set screws. All the set screws and mounting bolts are 3/8-16. The bolts for the individual knuckles are 1/4-20 but once assembled, they are left alone and set with locktight.

To set it up and take it down, I only need one Allan wrench. The mount the tooling in the holder I need another.

The shaft diameter is 1" and the height is pretty easy to set. Once the height is set to a particular lathe there is never a need to re-set it unless I have a goofy tool or I want to change the height - - maybe lower than center, some guys prefer that. The thing mounts and dismounts with no change in the height. So it's once and done.

 

[Glen Blanchard]

Way cool! Looks very much like the Kobra!

 

[Hu Lowery]

bearings and copies

Thanks guys. The diameter of the knuckles was dictated by the tapered roller bearings. I got 'em dirtier than dirt cheap; couple of dollars apiece. They were designed to replace the pedestal bearings in a Ferris Lawn mower. I don't think I'll ever load 'em to factory spec'.

My welds are horrible looking, but have good penetration. I'll do something to clean them up for paint. Grinding & silver solder or just bondo.

Now, I gotta design some tooling for it.

Raul,

Even going commercial which you have given no indication you want to do I wouldn't sweat the "copy" issue. Enough changes from the unit this seems to be the closest copy of to easily patent this design.

When I read this used tapered roller bearings I figured you had "nice priced" them one way or another. I used to own an auto salvage and many things that were too pricey to buy new were crushed. I could have salvaged dozens if not hundreds of identical GM tapered roller bearings from the front spindles each year as one quick thought. I often consider old AMC spindles for heavy duty turntables. The spindle itself mounts onto the arm with four bolts and is great to make trailers out of, four of them work fine for hauling thousands of pounds. Would work fine for a lathe spindle as would the 3/4 and 1 ton full floating rear spindles and hubs. If I still had a medium sized metal lathe I would probably build a monster wood lathe just for grins.

I was kinda watching e-bay thinking about inline bearings for a hollowing tool. Someone has went to market with the idea now or is near that point. My idea came from my NC router long before I read of someone else using the inline bearings but I suspect the biggest problem I or they will have is finding the bearings at a price they can market the unit.

Have fun with your design for your own use and if you market it I'm sure there will be good demand. As you say, being able to take the lash out of the bearings is a big deal.

Hu

 

[Bill Boehme]

Really nice machining and design work, Raul. I noticed in the short video that the tool bar touched the tool rest on the right side, but went over the left side without making a sound. My thought is that the lathe bed isn't perfectly flat and that the toolrest probably isn't perfectly parallel to the bed at the point where the banjo is locked down. With the articulated arm being so rigid, is there a problem in having just the right amount of contact force between the tool bar and the toolrest ... or would that be the reason for the gate?

BTW, for the benefit of Steve and others with the implied question about patents, the concept of an articulated arm assembly-isn't patentable, but the actual implementation might possibly be if there are components of the design that wouldn't be obvious ideas.

 

[Raul McCai]

One of the ways I tried to get a hold of the Kobra guy was by doing a patent search. I came away convinced he never bothered. There are patents on various systems one is on the market today and oddly, the patent is very different from the commercial version.

Ostensibly I could patent this design of mine by using a Utility Patent which would make some claim about the sort of bearing used in exactly such a fashion and how it does this or that. Well, I could have, right up to that point where I started posting it on the internet. Right there I lost my exclusivity. Once it's shared it's no longer exclusive.

I was with a big R &D firm in Boston years ago and we actually got a patent on the Swing Link using a utility patent. The Swing Link is that little arm you see on an old time Steam Locomotive wheel driving it. We patented it in a very narrow application driving an Involute Scroll pump.

But I ain't patenting anything. Been there done that and got nothing for all my effort. Nope, this is my tool for me in my shop. If anyone wants my drawings ( such as they are) they are on Photobucket.


I do think the Linear bearing idea that Glen mentioned is really slick. Two dust seals for each bearing and the thing is golden.

 

[Hu Lowery]

patents

One of the ways I tried to get a hold of the Kobra guy was by doing a patent search. I came away convinced he never bothered. There are patents on various systems one is on the market today and oddly, the patent is very different from the commercial version.

Ostensibly I could patent this design of mine by using a Utility Patent which would make some claim about the sort of bearing used in exactly such a fashion and how it does this or that. Well, I could have, right up to that point where I started posting it on the internet. Right there I lost my exclusivity. Once it's shared it's no longer exclusive.

I was with a big R &D firm in Boston years ago and we actually got a patent on the Swing Link using a utility patent. The Swing Link is that little arm you see on an old time Steam Locomotive wheel driving it. We patented it in a very narrow application driving an Involute Scroll pump.

But I ain't patenting anything. Been there done that and got nothing for all my effort. Nope, this is my tool for me in my shop. If anyone wants my drawings ( such as they are) they are on Photobucket.


I do think the Linear bearing idea that Glen mentioned is really slick. Two dust seals for each bearing and the thing is golden.

Raul,

I spent a few years in R&D myself. Everybody around me had patents, my friend and partner in crime on some projects had over eighty. Two made him money and one of the two paid him $25,000 a year for life. An oil company thought they made a slick move when he was pushing seventy and he bit on the yearly payment plan, they weren't as thrilled about the deal when he was pushing ninety!

Another friend sold the US rights to a pump for four million. A japanese company came to him and told him they would give him forty thousand for the overseas rights or just start making the pump and he could fight them in a japanese court. Don't know about now but then the japanese courts simply rubber stamped anything a japanese company did. Mr Leon took the forty thousand.

I have had a design stolen but I don't think having it patented would have mattered. Unless you manage to partner with an entity with the money to defend a patent they don't even make good toilet paper!

Hu

 

[Raul McCai]

Raul,

Unless you manage to partner with an entity with the money to defend a patent they don't even make good toilet paper!

Hu

Indeed.

Rare is the story of the little guy who can mount a successful patent fight. Everything is expensive, it can take years and years. Unless it's really worth the fight, why bother?