Newbie having trouble with lathe

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PaulSF

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Hi Folks,

I'm new to this, and I'm having some issues with my mini-lathe. I have the Turncrafter Pro, the kind where I change the belt position manually. I've got my pen blanks on the mandrel with bushings in the proper place, everything is tightened up and spinning nicely, but when I put the gouge to the blank to round the corners, it stops the blank cold. Everything else is still spinning away, but the blank isn't moving. I've sharpened the gouge and adjusted the positioning, but these darn blanks just...stop.

Any thoughts as to what might be happening, and what I can do to overcome this?
 
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Wheaties

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Two things come to mind:

1) Your bushing are not tight enough
2) Your loosing your glue bond, so the tube is tight on the mandrel but the tube lost its bond with the blank

Either of those?
 

PaulSF

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The glue bond issue did occur to me. I'm using the epoxy, and I started working with these blanks after the epoxy had set up for only three hours. I had better luck with some blanks that had sat overnight.

How do I tighten up the bushings? Do you mean everything needs to be tighter on the mandrel? I've turned the tightening knob pretty hard.
 

Wheaties

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Well you don't want to over tighten them. If you can't spin the blanks by hand after tightening, it's plenty tight.

Are the bushings right up against the brass tubes? If there is a little bit of wood between the bushing and brass tube, that could be your problem.
 

ed4copies

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Paul,

Welcome!!

WHEN I have that problem, which is frequent, it is because my knurled knob has reached the end of the threads BEFORE it has made GOOD contact with the bushing. Add another bushing (spacer) and try.

Works for ME-----OFTEN!!!!
 

PaulSF

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Thank you! I just glued tubes into a couple sets of blanks, and I'll try again tomorrow after the glue has had the night to set up.

I appreciate the help. I've actually been browsing the forum for a while now, and I'm in awe of some of the work I've seen here!
 

PaulSF

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Paul,

Welcome!!

WHEN I have that problem, which is frequent, it is because my knurled knob has reached the end of the threads BEFORE it has made GOOD contact with the bushing. Add another bushing (spacer) and try.

Works for ME-----OFTEN!!!!

Wouldn't you know, they only sent me 5 bushings! But I've got more on the way, and I may still have a handful at home from the classes I took at Woodcraft a year or so back.
 

ed4copies

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Drill a 7mm hole in a small piece of wood, mount it at the end next to the knurled knob---doesn't have to be pretty, just needs to make everything snug.
 

DozerMite

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Just a short piece of 7mm tube will work for a spacer too.
Or go to between centers and eliminate the mandrel.
 

Wild Ed

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I had the same problem when I first started turning pens. Had the lathe set at a very slow RPM which I always used when turning large diameter spindles. I then set the lathe to 3300 RPM and have had very few catches or blank stoppage since.
 

glycerine

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Also, just use super glue (CA glue) to glue the tubes in. When I started, I started with epoxy thinking it may be better to have something more "flexible", but I've had a much easier time with super glue...
 

ldb2000

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Then most likely you are just being to aggressive with your cuts and/or using too slow a speed . When you are just starting to round down the blanks you should be using the highest speed your lathe spins at and take very light cuts . A slow speed will allow the blank to catch very easily and trying to take too much off on those first cuts will just compound the problem . Different kinds of woods will require different amounts of pressure to turn them down so always start with light cuts and add pressure as you learn how the different woods react .
As Ed said , make sure that you have not run out of threads on the mandrel , the blanks should be tight enough not to spin by hand but not too tight . If you don't have enough bushings you can use a few washers at the brass nut end of the mandrel . Do not over tighten the mandrel nut (the brass nut) or you could flex the mandrel and create out of round pens .
 
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PaulSF

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Interesting, because the instructional material I got said to use 500 rpm when rounding off the blanks, and to increase the speed after that. I'll give it a try tomorrow. Thanks!
 

leehljp

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Interesting, because the instructional material I got said to use 500 rpm when rounding off the blanks, and to increase the speed after that. I'll give it a try tomorrow. Thanks!

It is good to follow what you read until you get experienced enough to know what to ignore! :biggrin:

Nothing less than 1000 for me for starting. 2000 is even better.

I will give you a hint as to why the 500 was stated: Many people who are into bowls and spindles start at that speed, and slower, and transfer this practice onto pens. This does not take into account the smaller size of pen blanks. It is much more advantageous to use higher speeds on smaller diameters such as pen blanks.

As an analogy, router bits that are 1 1/2 inch or two inches in diameter are recommend to run at 8000 RPM or so. 1/4 inch are bits are rated at 20,000+. The speed of the edge of a pen blank turning at 2000 RPM is approximately HALF the speed of the edge an 8 inch bowl turning at 500 RPM, and that is why it is "catching".

Turning a pen blank at 500 RPM create the same speed at the point of the chisel as turning an 8 inch bowl at about 60 RPM - waaay too slow.
 
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PaulSF

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SUCCESS!!

I created a new bushing using a spare stretcher bar key and upped my speed, and it worked just fine. Made two more pens this morning!

Thanks guys!
 

fstinard

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Paul
If you advance to other turning starting your roughing at lower speed is fine but with the small pices you need to incress your rpm to turn and lower it to sand
Fred
 
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