Monster Articulating Depth

[Bill Hensley]

I know there was discussions and some of you have upgraded the arm on your Monster to 1". Now that you've had it a while do you see an ability to increase the depth and stable performance?

I'm getting a little frustrated with the depth limitations, ~8" max before I get into the "forgetabout zone", but otherwise I have NO complaints about the system.

All input appreciated!

[John Keeton]

Bill, your 8" depth with the 3/4" bar is about right. I recently acquired the 1" bar in conjunction with the captive system, and that setup works great. The last piece I did was 13" deep in end grain. I did get some bumpiness in the bottom, but with care, it worked fine. I have not used the 1" bar on the articulated system yet, so I cannot comment on how much more that will give you. However, given my experience with the captive system, I would imagine it would extend you to 10-11" perhaps.

[Jim Burr]

No hijack intended Bill, but just got word that Randy's daughter Michelle and her husband are re-locating Monster to Colorado...have the shop space and everything. There was a question for a while if they would stay open, but this is good news for all indeed!

[Reed Gray]

While I don't do many hollow forms, I do a few. I prefer to free hand rough with the Kelton hollowers, and finish cut with the Monster. I do really dig in when roughing, and the Monster won't take that, especially over about 6 inches deep. It works fine for light cuts to maybe 8 inches, then it starts chattering. As I said, I am rather heavy handed.

robo hippy

[David DeCristoforo]

I have found that whenever you get much beyond 6" in depth, you can start to get some bouncing and chattering. The 1" bar should make a big dif over the 3/4" bar but since I don't have a 1" bar, I can only take the word of others on that! But here is one thing I have "discovered". The rig works best if the cutter is on the center line. But if the relationship between the tool rest and the arm support (with either the articulated or captured rig) is not such that the bar is parallel to the lathe bed, the cutting tip can drop below or rise above center as the depth increases. The result will be that you get pounded! I find that I can cut slightly above or slightly below center without any chatter up to a depth of around three inches. After that, it starts getting bumpy. So it's more important to have the cutter on center as the depth increases. Now, after I get down into the form, I stop, remove the whole thing (just unscrew the chuck) and pop a center into the spindle. Then I reset the rig so that the cutter is on center at the bottom of the form.

[Jeff Myroup]

With a small hunter carbide tip (stolen from my jammison rig) I go almost 12" with the standard 3/4" monster rig. The tip is pretty small and I take light cuts. As long as I keep it on center, I have no problem. I normally don't turn super thin as my hollow forms are mainly urns.

[Jamie Donaldson]

David- 'splain please about how you "pop a center into the spindle?" :confused:

[Roger Chandler]

I can go deeper........of course I have a bar made for me by a friend who is a machinist..........my bar is rectangular in shape and flat on one side..........the stability improves over the stock 3/4 round bar considerably. My bar is 24" long and I can hollow 16-18 inches.

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[David DeCristoforo]

"David- 'splain please..."

Well... OK. I remove the chuck with the form still mounted. Once the chuck is off, I put a drive center in the spindle. In this instance "pop" and "put" are interchangeable. I align the cutting tip with the center point. Then I "pop" the spindle back out (remove it from the spindle) screw the chuck back on and go.

[Bill Hensley]

All, thanks for the info.

Roger you had sent me some info on the bar so if they are still being produced that may be the way to go.

Agreed, I've found being on center gets the best behavior.

[Rich Aldrich]

Great idea. You could take it one step further and use the same method to check the level of the bar if your lathe has a sliding head stock. If you checked it with the head stock near the tool rest, then near the middle point of extension and then with the arm extended near the limit, you would be sure it is set level. Of course, there may be easier ways.

[Eric Holmquist]

I suspect that this is a more generic issue with boring bars, than a Monster issue. I made my own articulated arm system, and I find that I have to use an increasingly lighter touch as I go past 6" using a 3/4" boring bar. It is difficult to make the system chatter under 6 inches, but fairly easy to make it chatter at 8" deep.

I have not tried to go deeper than just under 9" as I need to make a longer boring bar to try that.

I have not tried a Hunter Carbide style cutter yet, I need to make a holder for the cutter that I have first.

[Roger Chandler]

I suspect that this is a more generic issue with boring bars, than a Monster issue. I made my own articulated arm system, and I find that I have to use an increasingly lighter touch as I go past 6" using a 3/4" boring bar. It is difficult to make the system chatter under 6 inches, but fairly easy to make it chatter at 8" deep.

I have not tried to go deeper than just under 9" as I need to make a longer boring bar to try that.

I have not tried a Hunter Carbide style cutter yet, I need to make a holder for the cutter that I have first.

The thicker the bar the deeper you can go when hollowing............it is an issue of length past the tool rest and the thicker bar will not flex as much...........also, if you can get one of those tool rests that go inside a turning, then you get support at deeper than just the opening............I think Best Wood tools carries one if I remember correctly.

[Chris Colman]

With my homemade articulated arm I have found that when deep hollowing it is not so much the diameter of the bar, but the percentage of the bar overhanging the tool rest. I made my original setup with too short a bar.

When I get into the 6-8 inch range I switch to a longer bar, so that the leverage is better.

[Steve Schlumpf]

Bill - just my experience, but when hollowing, the deeper you go, the smaller the bit you should be using. I have both of Randy's systems and do probably 95% of my hollowing with the captured system... it is what I started out on and what I am most comfortable using. When you get to the 8" to 9" deep level, you really have to make sure that the cutter is at or slightly above center or it will bounce around on you. I have the best luck with the cutter slightly above center because the bar will flex... which results in the cutter being dragged to below center. When that happens, the bit no longer cuts until the bar bounces back to center or above... and then you have a grab/catch when it digs into the wood.

Best suggestion - sharp cutting bits, positioned slightly above center and make light passes. Takes longer but you will get the job done!

Good luck!!

[Eric Holmquist]

When you get to the 8" to 9" deep level, you really have to make sure that the cutter is at or slightly above center or it will bounce around on you. I have the best luck with the cutter slightly above center because the bar will flex... which results in the cutter being dragged to below center. When that happens, the bit no longer cuts until the bar bounces back to center or above... and then you have a grab/catch when it digs into the wood.


An excellent point, I had not thought of the flex factor pulling the bit down into a no-mans land

[Bill Hensley]

Agreed, excellent point. I'll adjust my setup the next time. Thanks Steve.