a bit confusing and 15 bf later

allen levine

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I didnt want to come onto this end of the site and start with all the beginner questions. A few about chucks and lathes, but figured Id wing it from there.
After alot, and I mean alot of attempts today and tonight at chucking up all size blocks and dowels, I finally figured I can get something cooking.
I seem not to be able to rechuck a squared piece exactly, so I rounded over a square long piece.
Then I cut out a simple knob and instead of doing anything to seperate on lathe, I decided to take out of chuck, and cut off with enough extra for mistakes.
So I had the perfectly round piece, a knob cut out on one end, cut it off, made sure the cut was 90 degrees, and rechucked it with other end so I can dig out a little of the face of the knob.
Problem is, it keeps coming out off center and I cant figure out why?:dunno:
Its the same size round piece, I purposely left an inch of same size to rechuck exact same way, and I cant carve out dead center.
What am I doing wrong?
I think I used 15 bf of spanish cedar today to get one knob which I havent gotten yet. I had alot of them crack off, one flew out of chuck.
This is what I mean off center.
 

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Allen
I haven't turned much but I can tell you from my metal lathe experance its very hard to re-chuck any thing and be concentric. You do everything you can with one chucking. And if you need to re-chuck you often improve things thing by re-chucking exactly as it was before.

A four jaw chuck will let you recenter and I have seen these for wood.

I suspect the woodturners will have much better advice.....

Garry
 
Allen, I'm not sure what might be causing the problems you're seeing, but I wonder if it's how you're gripping the piece of wood in the chuck. Although it seems counter-intuitive, you don't want the wood to bottom out in the chuck jaws. Instead, you want the face of the jaws to be resting firmly on the should you have cut when cutting the tenon for the chuck. This sketch helps show what I'm talking about:

Chuck Tenon Grip.jpg

Does this resemble what you're trying to do? If not, show a few pics of the piece on the lathe. That should help is troubleshoot the problem.
 
OK here goes, maybe this will help.

Round the piece from end to end.

On the end away from the chuck (this will be the bottom) turn a dovetail tennon, so the chuck has something to hold onto. Use your parting tool to identify where the bottom will eventually be, by making a shallow cut.

Now, cut the blank off at the height you want the piece to be.

Chuck up the tennoned end and adjust to run true.

Turn the cup into the end.

Sand and finish.

Part off, angling towards the center so that the outer edges sit flat.

That's the way I do it.

Bruce
 
Vaughn, I was bottoming it out, but I was cutting it 90degrees on mitre first.
Bruce, without cutting the dovetail I was chucking it, then figured Id just use an inch extra and cut off. but your way makes more sense.

I think I discovered the problem with my approach.

When first cutting round, I spun between centers.
My mistake was I was using a fine point sharpie, since I cannot visually pinpoint the center with pencil, and just spinning spindles were fine like this.
But rechucking it, off that tiny cm(mm) or 2, it then spun a bit off center from the original spot.
I didnt realize how drastic any off center could result in rechucking it.(at least I think that was my problem)

I got the solution, Bruces way seem easy enough once I gain the talent.

IM sorry about the stupid question, I will search more and practice more before asking first grade questions.
 
Allen, you haven't asked a stupid question yet. I don't expect you ever will. ;) We're all getting too old for this trial and error stuff. Take advantage of those who've of us already tried and erred. :D

Vaughn, I was bottoming it out, but I was cutting it 90degrees on mitre first...

That still doesn't really work very well. The chuck gets a LOT of its holding strength and stability from the face of the jaws pressing against the shoulders. The gripping of the jaws is largely just to hold the shoulders to the face of the jaws, not to hold the tenon by squeezing it. Always leave a gap between the end of the tenon and the bottom of the chuck jaws. The only exception I can think of is if you're holding square stock. For me, in those cases I'm turning the whole piece with the tailstock in place, or I'm only holding it that way long enough to cut a tenon on the other end (and I still have the tailstock in place). If I want to hold the piece without a tailstock, I make sure I have a round tenon with a good shoulder.

Bruce's suggested method will get you headed in the right direction. And keep in mind that pretty much any time you chuck or re-chuck a piece of wood, it'll need to be trued up, at least a little bit. (That's been my experience, anyway.)

And to drive home a point a bit more, go re-read the first sentence in this post. ;) :) :wave:
 
Allen, no dumb questions. In fact, I have chucked a few things on my lathe in my chuck. But still learned some new things from this post. Keep on asking, if you aren't asking you aren't using your lathe, then if that happens you might as well send it to Larry so it can collect dust on his workbench!!:rofl::rofl:
 
My tip of the day:D

If you think you are going to have to rechuck something mark the jaws and their placement on the wood. When you use a compression with a tenon the wood will be squeezed, probably different amounts by each jaw as it is never the exact same density all round so when it goes back in the tenon is misshapened. If you can put it back in where it came out in relationship to the jaws you should find it is far closer to centred.
Another tip is to mark the centre of the wood if possible before taking out and use the tail to centre up before tightening the jaws when rechucking.

Pete
 
thanx pete, I did that right away, marking it. I put a tiny piece of blue painters tape on the chuck, and made a pencil mark on the tenon so I could rechuck same spot.......today I went basically with Brians method, and everyone else who told me and realized after chucking I have to round over again, before I start any shaping. 3-4 hours yesterday, 3 hours this morning, I finally got 2 knobs, the most simple of simple knobs, but they are somewhat close, my daughter was home for lunch, said they are fine.
Two dollars worth of store bought knobs, I spent a day and Im still off.
IF I could have lifted the lathe, I would have thrown it.
I started a collection of all the pieces of cutoffs and mistakes, I think its taking on the look of a chess set ready to be made.(maybe in 20 years from now when I know what Im doing)
Im thinking Id be smart if I just bought three metal knobs for the inside drawers. At the rate Im going, it could be 8 weeks more.

on a positive note, my scrap bin is finally seeing action and is empyting quickly.
I also messed up the small gouge on the grinder today. I had the right angle set and everything, but I moved a bit, and lost the curve at the tip. The more I tried to get it back, the more damage I did.
I see some kind of jig in my near future, or at least before I get any good chisels. It did cut like a razor though.
 

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Allen, It is difficult to re-chuck even metal and get it true without using a dial indicator and "tunking" the item back true. Since wood does compress this makes the job more difficult. I do turn multiple items and re-chuck them. I made a collet out of hard nylon and this helps because the wooden diameter just slides into this hole, whereas the chuck rarely matches the wood diameter. I then chuck up on the nylon and hold a pencil near it until it starts to just hit. This shows the "high" spot. "tunk" it a little to true it up.

The collet is made with the inside hole matching the outside diameter of the pegs or drawer pulls I am turning. I then slot the nylon (2 slots)with the band-saw so that you nearly saw it in half (but not quite) from each end but at 90 degrees to each other.

Hope this helps.
 
I learned a powerful lesson today.

Today I learned just how powerful my tiny little lathe can be.
A while ago, I showed a picture of a block of maple and mahogany, scrap boards I glued up to make a lamp. I tried to cut it in a round fashion, but gave up. Vaughn had mentioned hey, Allen needs a lathe.
Anyway, I had glued it up where I left a 1/2 inch or 3/4 inch space in the center to pass a tube and wire for the lamp so I wouldnt have to drill it after.
It was a failure, the project, but I just sanded it lopsided, put a base on it, and called it art/sculpture, as a joke, and its been sitting on the floor since.
Last night, I cut wedges, out of mahogany scraps, hammered them into the holes tight with glue and let it dry overnight. (must have gone down at least 2 inches into each side so there was plenty of wood)
Today, I cut the wedges, made sure the ends were flat, and mounted it onto the lathe. Gave it a few spins, seemed centered, all ready to go.
I turned the speed dial(variable speed) all the way down like I always do, but it was still too high so I had to change the belt to the slowest speed.
Got it turning, slow, started to trim it, as soon as I got the chisel and made a few shavings, the center on the headstock collasped the wood wedge I had, the lathe shook violently, jumping up and down as I went to hit the off switch, it launched that heavy, heavy piece of wood. I didnt get hit, because as soon as it started to shake, I stepped off to the left.

But I cannot believe the force at which that heavy chunk of wood flew off the lathe. Like a cannon ball, and I have a little tabletop lathe.
Nice reminder what Im dealing with, stupid I tried to recut it, but I just wanted to cut a tenon to mount in chuck.
It only took a split second between collasping the center to launching it.
btw, after today, Im ordering a much more substantial face mask than that plastic shield I wear, Now Ill go for the 50 bucks, just needed this cannonball to show me how stupid I am to think my flimsy shield will help.
 
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Allen,
I didn't read each and every post before I responded, so you may already have this as an answer... but what I would do if I were doing what you are

1. round the square stock at least where it will be chucked...
2. cut a tenon to fit in the chuck just less than the depth of the jaws on your chuck... leave a small shoulder to fit against the top of the jaws.
3. If you have to unchuck it for any reason, take a pencil and mark the location of one of the jaws... I always use jaw number 1...
4. that way if you put it back on the chuck you'll be very close to the original position.

I suspect the off center you are experiencing is that the piece is bottoming out on the jaws and even though you think you are 90 deg... even 1 or less degree off will create a wobble and off center cut. (DAMHIKT)
 
thanx pete,
Snip
on a positive note, my scrap bin is finally seeing action and is empyting quickly.
I also messed up the small gouge on the grinder today. I had the right angle set and everything, but I moved a bit, and lost the curve at the tip. The more I tried to get it back, the more damage I did.
I see some kind of jig in my near future, or at least before I get any good chisels. It did cut like a razor though.

Allen
Here is another use for your scrap box, a jig that even I could build. He actually want 5.00 dollars from plans, but I can't see why you would need then. It a wood version of the common jig. Similar to what Stu and others have posted. But simple as they come and looks as if really works well in his video..


http://www.youtube.com/watch?v=VgeeBJSCC0E

Garry
 
IM sorry about the stupid question, I will search more and practice more before asking first grade questions.

Allen,
I have to agree with Vaughn, there is only one stupid question.... that's the one you didn't ask.

I've gleaned an incredible amount of information from reading all the questions and posts on this site.... it's my first stop every morning to see what I can pick up as new info before I go out to the shop.

This forum is a fantastic source of information..and inspiration... :thumb::thumb::thumb::thumb::thumb:
 
Today I was determined to cut down stock, walnut, maple, white oak, mahogany, etc....and make 6-8 pens.
I cut down 4 pens worth, 8 sides, trimmed them with the tube trimmer, inserted tubes, glued it all up, and started to spin.
First of all, I had no idea the kit I bought had 5 pencils and 5 pens, I thought I bought all pens. Not a big deal, but suprised me after the first one.
Put together the first one, made of mahogany, I noticed a tiny chip out, I was going to try to dissassemble(it happenned when I squeezed too hard)
but my wife wanted no part of it, she wanted the pencil and told me Im crazy.
Then I started to spin pens. I blew out the first one, it split. I recut another piece of walnut, it split while spinning. I did it again, it split, and each time I managed to get the tube by sanding the walnut off. Finally on about the 5th attempt, the tube was a bit dirty, I tried to force it into another walnut blank, and that was that.
This was taking me quite some time, cutting down scraps for pen blanks, didnt realize its pretty time consuming. It was nice having all those rosewood blanks in the pen kits, but Id rather save those for when my family wants to spin a pen and give it a try.
I closed up, but hated leaving on a bad note, so I took out another set of blanks, the white oak, and this pen came out nice. So nice, Im keeping it for myself. I aint making no show pieces, but its cool all the same. I like it.
I also was making cutting boards today, so I was fairly busy. I destroyed my 1/4 inch blade on the bandsaw attempting to make the Glen Bradley type candle holders, and Glen told me what I was doing wrong. I then tried again this morning,(before glen contacted me, I thought I had it figured out, but I was wrong again,) destroyed my 3/8 blade, destroyed my rubber tires on the bandsaw, and will have to buy new ones, all because I failed to really pay attention to one thing and that was my downfall. Glen has set me straight, so when I get some new blades and new tires, I will attempt it again.
gonna be some expensive candle holders, wish I had glens knowhow.
This is a days work. Not too impressive. A very expensive day for me. Live and learn.(I took 2 closeups of the pens, ofcourse my hands shook and the picture failed)got my pen on the floor.white oak.
 

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Allen,
If you're splitting blanks as in the walnut, I would guess you may be getting a little too agressive with your tool.... which tool do you use to turn the pens?? I'll round them to get the corners off with a round nose scraper, then switch to 1/2 or 1 inch skew to finish the pens... I like the skew because I get a better surface towards the end and can match the bushing better. I've always used a mandrel, but just recently bought a dead drive center so I can turn pens between centers... less likelihood of getting an oval pen - so I'm told...

BTW, those are some nice cutting boards....
 
I use thick blanks, so to take them down fast I use a large gouge.
Then I switch to a small gouge or just the skew at the end. Never used a scraper for them.
btw, I try to get the fatter part in the middle. the 3 or 4 Ive made so far everyone likes the look and the grip. ONly my wifes I made slim.(I only have a 7mm mandrel, came in the kit, Im pretty satisfied with it, easy to use, works well. I color the bushings with a black sharpie so I can tell when I get down close.)

Busy going through every piece of short of scrap I have this morning, making boards, figured eventually they will be gifts.
I ordered 20 pen sets, slimline again, cheapos, but I forgot to order friction gloss. Im going to spin them set them on nails through a board, and use wipe on gloss poly, since I intend on doing 6 or so at a time. No rush.(Ill order friction poly or shellac next time I place an order.)
 
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