Mandrel Work Holding

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MourningWood

MourningWood

Member
Joined
May 26, 2021
Messages
3
Location
catawissa, PA
Hello everyone,

I'm new to pen turning and turning in general. I actually made a pen for the first time two days ago, but I had a question about using a mandrel. I successfully held the two pieces of wood and turned them down, but not before I had to crank on the tightening knob to get the pieces to not rotate around the mandrel. When I went to remove the pieces, a little bit of the brass tube was left on the threads in the form of a ring. So my real question is how are you people that have been doing this for years getting the mandrel set up. The first time I did it while not tightening it like this, putting the tool into the wood acted like a stopper. Any help is appreciated!
 
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With the mandrel saver you are putting the pressure on the bushings and not on the mandrel rod. This prevents bending the rod from bending and creating off center turnings. Keep at it you will get better.
Turncrazy43
 
There are 3 basic reasons that I can think of that would cause you to tighten the brass nut that much:

1. Being new, your first blank was a rock hard wood such as desert ironwood, and you are unfamiliar with adapting to the individual blank.

2. Your tools are too dull. This is the most likely. Many people new to turning do not understand the need for precise sharpening. Did you sharpen the tool before using? It does NOT come sharp as it needs to be straight out of the box, UNLESS it is a carbide insert.

3. Feed rate TOO FAST. In other words, Taking too much of a bite to quickly. It is not an instant thing as in cutting a board with a saw. (This is the second most likely reason) Feed rate into the blank should be slow - and that description is very subjective. Take small bites with sharp, sharp, sharp tool and run it along the tool rest, just barely cutting the edges off and gradually turning the blank round.

Ken gave some good advice on getting a mandrel saver.

Another method besides the mandrel saver is TBC - Turing between the centers of the tail stock and head stock. But you would have trouble with blanks spinning too - if you are having trouble with currently.

Since you are new, DO NOT learn by turning to the size of the bushings. Get a good pair of metal calipers and measure the turnings to the size of the center band, nib/nose cone and clip end. Bushing shoulders WILL shrink in size as the chisel touches it while turning and also when sandpaper hits it while sanding. After 15 to 20 pens, the shoulders will be visibly smaller, resulting in a poor fit to the pen.

Harbor freight has some decent metal calipers on sale occasionally for $10 - $15.
 
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You do have to snug up the nut pretty good, but should not have to really crank it. Maybe you were a bit too aggressive in the amount of 'bite' taking when approaching the wood with the tool? Just some thoughts.
 
I can not improve on what Hank wrote. He's always clear and to the point.
And yet I'll chime in ;) since I've been thinking about this and have some half-made graphics laying around.
My experience is there's a relationship among the 3 factors Hank laid out: Tool Sharpness, Clamping Pressure, and Feed Rate.
If I'm deficient in one area I can usually get away by overcompensating in the other two categories. For instance:

1. My Tool is Dull
I can make it work if I really wrench down on the clamping pressure (not recommended) and take tiny bites on each pass (slow feed rate).
a1.jpg

2. Too Little Clamping Pressure
Works (somewhat) if my tools are razor sharp and I take small bites.
a2.jpg

3. Too Big a Bite
If my tools are sharp and I overdo the clamping I can bust through the wood.
a3.jpg

Conclusion: Obviously it's a "false remedy" to apply too much pressure to the mandrel nut.
It's better to have sharp tools and make reasonable cuts for the wood density.
Overtightening too much, as you've noticed, bends the mandrel sooner rather than later.
My personal approach is to tighten it as little as needed after making sure my tools are sharp.

Lastly: I enjoyed turning much more after I ditched the nut and began using the mandrel saver folks above have mentioned. I'm a fan.
Best,
Cullen
 
Wmcullen said:
I can not improve on what Hank wrote. He's always clear and to the point.
And yet I'll chime in ;) since I've been thinking about this and have some half-made graphics laying around.
My experience is there's a relationship among the 3 factors Hank laid out: Tool Sharpness, Clamping Pressure, and Feed Rate.
If I'm deficient in one area I can usually get away by overcompensating in the other two categories. For instance:
Click to expand...
Cullen,
Do you do illustrations for a living? WOW! Exceptional and Clear! THANKS!

I am going to reference this thread in the future!
 
leehljp said:
Cullen,
Do you do illustrations for a living? WOW! Exceptional and Clear! THANKS!

I am going to reference this thread in the future!
Click to expand...
Thanks Hank. I had these graphics mostly done already. It was going to be part of my April Fool's Mandrelorian post but it was rough and the post was already running long... so I cut it. Your post gave me the last bits I needed to tie it all together (Thanks!). I'm fortunate to have some good graphics software, like Adobe Illustrator and Photoshop.
 
Hi everyone,

Thank you for all of the replies, this was awesome to come back to. I'm going to check out that mandrel saver, such a great idea!

I am definitely still learning how to turn and I'm using a box of random assorted blanks of different kinds of wood. Doing so, I haven't noticed too much of a difference yet. Any issues I immediately blame my technique in general. I'm also using a set of carbide insert tools I got on Amazon since I am still building my tool collection and have no way to sharpen traditional tools. I do wonder though, am I limited in the long run this way? I have a square insert roughing tool, a circular insert tool, and a V insert tool for parting.

One final question I have (for now!) Is about the tool rest. Is there anything to keep the shaft of my tool gliding along it for long periods of time, or do I just need to sand any nicks and dents out of it. It feels like there is always one spot or two that my tool sticks.

Thank you all again for the feedback. It is appreciated!
 
I have both carbide and traditional tools. I find myself using the carbide more than my traditional ones. Personally I don't care for the square carbide. I prefer the square with a 2 inch radius. Just a preference though. I can achieve a " no need to sand" surface with carbide and no need to sharpen continuously. That's why I lve gravitated towards them.
 
MourningWood said:
I'm also using a set of carbide insert tools I got on Amazon since I am still building my tool collection and have no way to sharpen traditional tools. I do wonder though, am I limited in the long run this way? I have a square insert roughing tool, a circular insert tool, and a V insert tool for parting.
Click to expand...
As Ken mentioned for himself (and me), square radius of 2" or 4 inch works better. A "square" requires precise movements or problems will arise.

"am I limited in the long run this way?"
It can be argued either way - yes or no. The correct answer is dependent upon the user's skills and what results one wants. The carbide inserts of 10 years ago were not nearly as sharp as the ones today, but, even today - you get what you pay for. The sharpest ones (from reading of others) generally cost more. That said, I sharpen my HSS tools razor sharp, and hone the tool with a couple of swipes - 3 to 4 times during the turning of a blank to keep it pristine sharp.

A very sharp tool (and that is subjective to most individuals) can turn the blank so smooth that it does not need sanding most of the time. IF you are doing segments, most of the time, sanding smears the surface of wood segments of different colors, and especially if there is metal in a segment. With very sharp tools, it can eliminate the sanding. For me, and a few others, HSS can be sharpened to a finer edge than most, if not all carbide, inserts. Ken's comments are about to win me over though. There comes a point in sharpness (and some carbides are almost, if not already, there) that it doesn't matter for the most part.
 
Just as I tell all new turners

Forget the mandrel ASAP and start turning using a dead center in the head stock, a live center in the tail stock plus special "TBC or Turn Between Center" bushings. They are different from the bushings you are now using. I admit to wasting a lot of time, mandrels, and blanks before I went to TBC. YES it will seem more expensive but your quality with immediately improve and you'll probably save money and therapy sessions by ditching the mandrel sooner rather than later.

They guy to buy TBC bushings from is Brian Nikitas. Search for him in the IAP forums. Two bushings (one in each end of a single tube blank) cost $18. For two tube blanks it is sometimes more as you might need three or four TBC bushings.

My biggest mistake as a new turner was the mandrel and second was dull tools.

Best of luck.
 
I disagree. I've been turning with a mandrel and bushings since I started turning pens over 20 years ago. I rarely have problems. I've only ever turned between centers once or twice, when I couldn't get the bushings, and needed to finish a pen. I was successful, but hated it. I much prefer bushings. I think it's better to give new turners options, and let them decide for themselves. Neither bushings nor TBC is right or wrong. It's whatever works for you.
 
qquake said:
I disagree. I've been turning with a mandrel and bushings since I started turning pens over 20 years ago. I rarely have problems. I've only ever turned between centers once or twice, when I couldn't get the bushings, and needed to finish a pen. I was successful, but hated it. I much prefer bushings. I think it's better to give new turners options, and let them decide for themselves. Neither bushings nor TBC is right or wrong. It's whatever works for you.
Click to expand...
I have read this quite often here, there and yonder over the years, however you did not mention to the new guys (and ladies) that your 20 years of experience tell you exactly what to do if there is a wobble, or how to determine if it is a bent mandrel, or too tight of tail stock, or using a non-60° live center in the mandrel cup, or manufacturers poorly made bushings. You could spot the quickly and good for you. Mandrel saver eliminates some of the problems, and TBC eliminates even more.

I much prefer HSS tools, but I have enough knowledge and equipment to sharpen them. The vast majority of people coming into pen turning do not have background experience in turning and don't even know the jargon for that matter, much less how to fix it. So, in spite of my preferences for HSS, I know those just starting out would benefit quickly from using carbide inserts, and I recommend those most of the time. Get on with the pen making and eliminate the bottle necks.

Some people will say: give them a choice and let them find out the hard way what works best for them, and in the meanwhile they can contribute to the economy as they spend hard earned money on items that in all probably cause problems, which will probably make them move on to something else.

It is not a simple matter of "what ever work," when it is costing time and money to the uninitiated. And, it is great that you already have that experience, but most do not.
 
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Hi Alex; Welcome! I live just north of Harrisburg PA. My one suggestion is to look for an Association of American Woodturners (AAW) club. All woodturners are more than willing to share their knowledge and expertise. AND nothing beats watching over someone's shoulder and asking questions. With the current situation I believe many clubs and professionals are doing remote demonstrations via Zoom. The club I belong to meets in Harrisburg at the Woodcraft store. We have been meeting on Zoom, AND OUR first in-person meeting will be on June 8th. Visitors are always welcome. This link will take you to the AAW club search page.

PM me if you want to attend.
 
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