Warning – Just had a Catch!

[Steve Schlumpf]

Was in the process of thinning down the inside top of a hollow form and felt the control arm rotate ever so slightly. BAM! Had a catch but didn’t blow up the form! Managed to push the cutting tip deeper into the form just as I noticed the rotation! Whew!

Still, it took some doing but managed to smooth out the ripped area inside the form and the thickness went from 1/8” to 1/16”! So, I guess the thinning part worked!

I have the Monster Articulated Arm Hollowing System and wanted to warn everyone to check the set screws that hold the control arm to the body of the articulated arm. See photo below. Like anything mechanical, things tend to loosen up over time when subjected to vibration. I do not have Lock-Tite on mine at the moment but will apply some later. I have labeled parts so everyone knows what I am talking about – even though some of the terms may be incorrect.

119490 119491 119492

Hope this warning comes in time to prevent others from experiencing the same type of catch!

[Randy Privett]

Steve.

You have one of the first of the Arms.The design has changed since then to help take care of the turning of the bar.

Randy

[Steve Schlumpf]

Oh... I didn't know that! Just assumed all the systems were the same.

[Bernie Weishapl]

I have had that happen a couple of times on mine Steve. I check it everytime I put it on the lathe.

[George Morris]

Steve one of my fellow wood turners has that unite for sale with the laser arm attachment do you think 275 is a fair price? Your form looks great good save! George

[Bill Bolen]

George, Monster has a heck of a good rep and the new price is right at $400 so I would jump on that if I were in your lucky spot!...Bill..

[Bernie Weishapl]

George if it were me I would jump on it in a heart beat. Very good deal.

[Mark Norman]

Glad you didn't blow up the piece Steve, looks real nice!

[Richard Madison]

Steve,
I think mine has a flat for the set screws. I did have a catch at the bottom of a piece (about 6" deep) and actually bent the extension (?) piece at the shoulder where it mates with the "control arm". Was working on that little nub at the bottom center where I should have drilled a "depth" hole if I had a longer drill bit or extension. Glad you saved your piece, which should be featherweight thin now.

[Steve Schlumpf]

Richard - I've never drilled a depth hole before - always seemed like a waste of time if I was going to hollow it out anyway. I use the laser to determine depth.

The little nub thing can be a pain to get rid of but I found a quick trick that works for me. With the lathe off - move the cutter so that it just touches the nub. Then move it off to one side and rub the cutter back and forth a couple of times and it will scribe a line. Remove the cutter, grab a flashlight and find out where the line is in relationship to the nub. Raise or lower your tool rest the distance between the scribed line and the center of the nub. Turn on your lathe and remove the nub! Works for me every time!

As far as the hollow form being really light - it's not. The top of it is 1/16" thick but the corner is closer to 3/8" as I couldn't get any of my cutters to reach any further into the area because the entry hole was to small. Could have enlarged the hole and used a collar - but I like the look of all one wood. The sides and bottom are 1/4" - so it is not as thin as I would like. Better luck next time!

[Ken Glass]

Steve,
I'm glad you didn't get hurt or lose the piece. It looks like its a beauty. I must also have the newer arm like Richard on mine, as it has a flat area where the sets screws lock down on the arm. I always disassemble my rig and store it in a box I made, after I use it, so I have to reassemble it each time I use it, and I have to tighten all the screws before use. That said I will check a few times during hollowing to make sure screws don't loosen. I also have a hard time getting the thickness where I want it on a small opening form near the shoulder area. Maybe someone has tackled this issue and solved it?

[Richard Madison]

Thanks Steve, that's a good tip. I'm never confident that I have the tool bit exactly on center line.

I have a short 3/4" long, 3/16" tool bit that's good for getting through small openings, but that's no help for reaching up under the rim. Sometimes a little tricky to snake the longer tool bit through the hole so you can then reach where you need to, but it gets easier with practice. Just takes some playing with the various bits, holders, and combinations thereof until you can pick the right one every time.

Ken, do you have the laser? Very cool. It's even handy for judging uniform wall thickness on open forms.

[robert hainstock]

mayby Randy would mill the flats for you and fix the problem. Last fall, I got a set of T handled allen wrenches from HF that realy speed up the whole allen wrench thing. They would be expecily nice for that "tighten every time" requirement. :)
Bob

[Allen Neighbors]

Steve and Ken,
I made a couple of small tools that will go through a 1/2" hole and cut just inside the opening and under the shoulder. One will go about 1/2", and the other one will reach from there to about 1-1/2".
The first is made out of a pair of curved scissors, that medics use to cut bandages away. The other is made out of a 1/4" rod, that I sharpened the end and bent.
I'll try to take a pic tomorrow, if you want... they're nothing special.

[Steve Schlumpf]

Allen - always good to see what others are using for tools! Problem I have is that I limit myself by the style of hollow forms that I like to turn. I like the smaller openings but have to have something that allows the cutters to reach 4" to 6" to hit the shoulder areas. Course, easiest thing to do would be to hollow through a larger hole and then use a collar to close it up. Oh well, it's always something!

[Ken Glass]

Steve,
I have seen a video that shows how to cut out an angled, substantial hole in the bottom of a form with a 1/2" hole in the top, hollow to 1/4", then replace the bottom without any noticeable line where the cut was made. I think it was a really large form also. I believe it may work with some woods, but not all, depending on grain alignment, etc. I will have to research where I found the video. My Granddaughters Birthday party at the riding stables take precedent today. If I don't fall off and break my neck, I will post a link later.