My hollowing rig

[Steve Krumanaker]

Here are some pictures of my deep hollowing set up. I have about 22" reach with it.

 

It's built around an inch and one quarter diameter bar. The bar is 4140 prehard steel. That should be stiff enough to reach out about 20" or so. I have about 22" of reach from the cutting tip to the torque arrestor that is welded to the round bar. There is a threaded stud in the front corner for attaching the laser pointer post.

 

 

 

 

 

 

 

 

 

 

 

This picture shows the threaded stud a little better. The trap that holds the boring bar is made from two 1" diameter black iron pipes. The top pipe is adjustable so the trap can accept larger or smaller diameter boring bars. Eventually I may add a 1 1/2" bar but I have no immediate plans to do so. If/when I do it will be a simple matter to use the same trap for either bar by loosening one bolt on either end and repositioning.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This is the "business end" of the hollower. The boring bar came from Grizzly as a set of five double ended bars. In addition to the angle slot the other end has a straight slot. I have both a 3/4" set and a 1" set of bars. The order from Grizzly also included 1/2" 3/8" and 1/4" boring bars. I could see no use to keep those so I gave them to my brother to use in his shop.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This is just a view from the tail stock end of the lathe. I figure I have probably less than $150.00 in this rig. For one this heavy duty, retail would be in the $500.00 range. With that said, I don't believe the retail ones are over priced at all. It's easy to look at material cost only and think they are charging too much for something like this.

In addition to my material cost there are several hours of machining that went into making this. My brother is no slouch at metal work. His normal shop rate would've pushed the cost of this well over what I would pay retail. Add to that, the cost of welding and there is no way it could be done for less. I'm blessed to have had someone to help me for hanging out together and a bowl or two.

Several times I showed my brother how others had made theirs. Always his response, well we're going to do it better than that. As an example, the trap on others I've seen simply used machine bolts and a bunch of nuts to make the assembly. Adjusting the size would involve tedious loosening and tightening several nuts. Either that or they were welded to fit one size only.

 

It will be a couple weeks before I get to try my hand at a deep vessel. I still have to make my steady rest and laser assembly. When I do get it all together  you've got to know, I'll post pics!!

 

Steve

[lew]

That is one beefy unit. 

 

Looking forward to seeing what you have in mind for the Laser.

[Cliff]

Sweet rig~!!!  4140 is tough stuff.  Miserable to weld because ya gotta pre-heat it to 600 or more  and ramp it down slowly or  else the welds can crack  DAMHIKT. They can be plenty strong welds cracks and all, but the cracks will fail an inspection and they are embarrassing.

 

It feels hardened to machine it in comparison to say - -  A36.  I can cut it with HSS but Carbide is better.

 

Why not skip the laser and go for BAROQUE~!!  Get a 12 VDC rear view camera and a little display and build your own version of the Trent Bosch Visualizer for like less than $50.00   That's the Bosch system is.

 

Edited February 21, 2017 by Cliff

[Stick486]

nice piece of engineering and execution Steve..

[Steve Krumanaker]

50 minutes ago, Cliff said:

 

Why not skip the laser and go for BAROQUE~!!  Get a 12 VDC rear view camera and a little display and build your own version of the Trent Bosch Visualizer for like less than $50.00   That's the Bosch system is.

 

 

 

I've watched a video using the camera method several times. I'm not convinced it's really better than a laser. That, and for what I have in mind I hope to eventually get final thickness using an LED. I don't know if it's possible, or maybe I should say possible for me but I'd like to turn 16-18" tall, thin enough to pierce.

 

 

 

Steve

[Grandpadave52]

Over the top Steve...I'll just pretend I really understand all about this...just don't tell anyone...Great thread post...FWIW, you've got the makings of another great blog entry here to be followed with your tool rest and laser set-up...I assume we'll get some video links once you start turning with this too...

[Stick486]

12 minutes ago, Grandpadave52 said:

I'll just pretend I really understand all about this.

thought it was just me...

[Kevin Beitz]

For your laser I would mount it in the rear so it doesn't get

damaged. Shoot it at a mirror that up front where things

are moving. And for welding 4140 if you use Nicad rods

you wont need to pre heat.

[lew]

1 hour ago, Kevin Beitz said:

For your laser I would mount it in the rear so it doesn't get

damaged.

Lasers are so inexpensive now, probably wouldn't be worth all the engineering.

 

$2.99

 

USB 5v power source and a series dropping resistor

[Kevin Beitz]

Nice.... 

Whats a series dropping resistor used for? 

Shut off shock?

[lew]

1 minute ago, Kevin Beitz said:

Nice.... 

Whats a series dropping resistor used for? 

Shut off shock?

These lasers are typically powered by 3 each LR44 batteries (1.5 volts each). The USB power brick supplies 5 volts. The series dropping resistor reduces the voltage from 5 volts down to 4.5 volts. The laser will last longer.

[Kevin Beitz]

Thanks....

[FlGatorwood]

Are there any photos or videos of this contraption being used?  

 

The fellow who gave me a few basic lessons had a similar set up.  It was impressive and made me realize the torque of the spinning wood.  

[Gerald]

You can get laser sighting doides  like this LASER and power it with a battery pack which Amazon also has or use a old power transformer. They work very well . I have one on my Elbo hollower for over 4 years.