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Forum topic by MikeinSC posted 03-31-2014 12:10 AM 1269 views 0 times favorited 17 replies Add to Favorites Watch
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MikeinSC

63 posts in 1451 days


03-31-2014 12:10 AM

I’ll make this short. I’ve started turning pens and have since bought 3 pen mandrels in the last few weeks. I’ve not begun to collect mandrels, it was because it appeared I was bending them. I am not over tightening either the brass nut or tailstock. I’ve since checked the mandrels against a dead flat piece of granite and can see no deviations on the mandrels.

So, I looked further and found this. When the head and tail stocks are lined up perfect, the mandrel will be just off center when used to turn a pen. But, when they are just off center of each other, the madrels line up perfecly.

The result is a turned pen that will be flush with bushings on one side and on the opposite side, will be just proud of the bushings.

The lathe is a HF 30704.

If anyone has any suggestions on how to cure what ails the lathe, I’d appreciate them. Except for buying another new lathe.

-- I am what they call a "rookie".


17 replies so far

View Jimbo4's profile

Jimbo4

1432 posts in 2226 days


#1 posted 03-31-2014 01:31 AM

Looks like to me like the tail stock is off center. From above in photo 2, I looks like the mandrel is “leaning” to the left, not being lined up with the dead center point. Looks like an adjustment for the tail stock. There should be a bolt on the bottom side of the tail stock to allow you to align it with. Might take some fair amount of time fiddling with it to get it centered.

-- BOVILEXIA: The urge to moo at cows from a moving vehicle.

View MikeinSC's profile

MikeinSC

63 posts in 1451 days


#2 posted 03-31-2014 02:40 AM

I will look into that. Thank you.

-- I am what they call a "rookie".

View MikeinSC's profile

MikeinSC

63 posts in 1451 days


#3 posted 04-01-2014 01:20 AM

The tail stock on this lathe does not allow for any rotational adjustmemnt. The bolt underneath is to adjust the tension on the tailstock when it is locked into place.

-- I am what they call a "rookie".

View MrFid's profile

MrFid

804 posts in 1367 days


#4 posted 04-01-2014 01:40 AM

You could try shimming your tailstock against the bed with a piece or two of metal cut from a soda can. Obnoxious to have to place it every time you move the tailstock, but that’s basically once a turning project. Less often if all you’re turning right now is pens. Price of owning a HF machine, I guess. How old is your lathe? I’d return that one and scour CL if you bought it recently.

Maybe others here will have better solutions for off-center centers.

-- Bailey F - Eastern Mass.

View Hilltopper46's profile

Hilltopper46

24 posts in 1063 days


#5 posted 04-01-2014 02:54 AM

If that is the live center that you are using with your mandrels, that is most likely what the problem is. You need to use a 60-degree live center with a pen mandrel. Not the point in the middle of the cup center that came with your lathe.

-- Turnin' and learnin'

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MikeinSC

63 posts in 1451 days


#6 posted 04-01-2014 02:35 PM

Thank you Hilltopper. I am using what came with the lathe and will look for what you suggested.

-- I am what they call a "rookie".

View William's profile

William

9906 posts in 2305 days


#7 posted 04-03-2014 12:27 PM

Can we get a photo of the whole lathe so I can see what we’re working with?
I can’t find that part number on the HF website.
It looks similar to my 34706 from harbour freight.
If it is I may be able to help.

-- http://wddsrfinewoodworks.blogspot.com/

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MikeinSC

63 posts in 1451 days


#8 posted 04-03-2014 12:31 PM

It is the 34706. I was going off memory when i wrote the original post and that seems to be flawed.

Thank you

-- I am what they call a "rookie".

View William's profile

William

9906 posts in 2305 days


#9 posted 04-03-2014 12:48 PM

Someone suggested a sixty degree love center.
They are correct. Order a sixty degree love center from penn state industries.
It’s less than $20.
The removable inserts in the original live center are not a true sixty degree, which is what you’re supposed to use with pen mandrels, and they don’t always run true.

Next, you have to get your points liked up.
There is no adjustment on the tailstock, but that lathe has a movable headstock.
It is supposed to have a lock for the standard position, bit there is always enough play to cause the issue you’re having.
Loosen the hold down handle on the bottom front center of your headstock. Move the headstock which ever direction you need to correct it.
Tighten down and recheck.
Often, it takes some playing with to get it just right.
On mine the headstock will move a tiny bit clockwise when you tighten the hold down. Because of this, I have to set it a tiny bit counter clockwise from where I want it and then tighten it down.
With practice, you’ll be able to tighten it down perfectly almost every time without all the fidgiting with it.

Does all this make sense?
If so, I will post next on how to straighten your mandrel.
You can bend a mandrel slightly just by getting a bad catch.
It can get mighty expensive replacing them everytime they don’t run true.

-- http://wddsrfinewoodworks.blogspot.com/

View William's profile

William

9906 posts in 2305 days


#10 posted 04-03-2014 12:58 PM

Mandrels get bent easily.
I knock mine out of wack on a regular basis because I like to turn burls, woods with voids that make them imbalanced and a host of other problems.

If you even think your mandrel is not running true, check it and fix if necessary.

Remove all bushings and mount your mandrel as you normally would.
This will only work after you get your centers aligned correctly.
Move your rest as close as you can get it to the mandrel shaft.
Turn the lathe on on it’s slowest speed.
Using the rest to keel it steady, lightly kiss the center of your mandrel shaft with a pencil.
Turn the lathe off.
Look at your pencil mark and it will be darkest where the high spot peaks on the shaft.
With hand pressure ONLY, push against the high spot on the shaft.
Wipe off your pencil mark, turn the lathe on, and mark it again.
Keep doing this until your pencil mark is as consistent as possible all the way around the shaft.
This tells you that spot is running true.
I like to check my shaft in several places along the length of it.

The first few times you straighten a mandrel shaft using this method, it can be aggregating.
It seems like you’re fighting a losing battle.
It’s because you aren’t used to how much hand pressure to out on it to straitened it.
You’re either pushing too hard or not hard enough.
With practice it gets easy to straighten a shaft in only a minute or two.

-- http://wddsrfinewoodworks.blogspot.com/

View knotheadswoodshed's profile

knotheadswoodshed

202 posts in 1635 days


#11 posted 04-03-2014 01:04 PM

I use this mandrel saver from PSI…works great and prevents any flexing/bending of the mandrel

http://www.pennstateind.com/store/PKMSTS2.html?prodpage=1PK

-- Randy - "I dont make mistakes, I make design change opportunities" www.knotheadswoodshed.com

View JADobson's profile

JADobson

681 posts in 1574 days


#12 posted 04-03-2014 01:30 PM

I have the same lathe, though mine is branded a King. I find that when you tighten down the headstock it shifts so you have to take that into account before you tighten the locking bolt. If you start with the HS and the TS perfectly lined up and then tighten, you lose alignment. If you place the HS a 1/16” towards you and then tighten the locking bolt it pulls it into alignment. You might have to play around to get it perfect but it is very annoying. I’m hoping to get a different lathe soon.

-- James

View TheDane's profile

TheDane

4997 posts in 3126 days


#13 posted 04-03-2014 02:27 PM

I have the same mandrel saver knotheadswoodshed provided a link to. I hate it.

The bearings are noisy, heat up quickly, and there is quite a bit of slop between the mandrel (PSI’s #2 Morse Taper Maxi-Mandrel) and the mandrel saver.

The slop causes vibration, which makes it nearly impossible to get a smooth finish off the tool.

This is the second one I have gotten from PSI … the first one had the same problem.

I use a 60 degree live center with my mandrel and have no problems.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View MikeinSC's profile

MikeinSC

63 posts in 1451 days


#14 posted 04-03-2014 03:43 PM

When the head and tail stock are lined up with each other, the pen mandrels do not line up with the tail stock as shown in the first picture. That is after the headstock has been locked down tight and then readjusted to make up for the headstock moving as it is tightened.

The first two pictures in the original post are when the two ends are lined up. And the last two pictures show how far off the the headstock needs to be rotated for the mandrel to line up with the live center.

I’m going to the woodworking store today after work. They carry PSI stuff so I’ll look for a new live center.

-- I am what they call a "rookie".

View William's profile

William

9906 posts in 2305 days


#15 posted 04-03-2014 05:08 PM

Line up your center points.
Then move your tailstock back and out in your pen mandrel.
Flex the shaft end as necessary to get the sixty degree center in it as it should be.
Check for trueness as I explained before.
It sounds to me like the mandrel shaft is not true along the length of it.
It only takes a tiny tiny bit to create the problem you’re having.
If you think about it, even if it’s untrue by one tenth of a degree, by the time you extend out five or six inches for the length of the shaft, that tiny bit will throw the end off enough to be noticeable.
Don’t be too concerned though.
I have three mandrels, one for my M1 lathe and two for the lathe with the M2 taper.
So far, none of the three have ran perfectly true when I got them.
I had to straighten them till they ran true myself.
This drive me nuts with the same problems you’re having until I figured it out.

-- http://wddsrfinewoodworks.blogspot.com/

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