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tenon removal problems

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Forum topic by Karda posted 07-19-2021 09:20 PM 964 views 0 times favorited 29 replies Add to Favorites Watch
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Karda

3353 posts in 1767 days


07-19-2021 09:20 PM

why is this happening. when I scrape the bottom of the bowl where I took off the tenon this happens, it is a gouge in one side some time it is deeper


29 replies so far

View Lazyman's profile

Lazyman

7801 posts in 2600 days


#1 posted 07-19-2021 09:43 PM

I assume that you reversed it to turn off the tenon and smooth it? How did you mount it? It seems to indicate that you didn’t get it quite flat.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Karda

3353 posts in 1767 days


#2 posted 07-19-2021 09:49 PM

I used a jamb chuck treaded on to the spindle

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bigJohninvegas

1083 posts in 2675 days


#3 posted 07-19-2021 10:39 PM



I used a jamb chuck treaded on to the spindle

- Karda

Yep, You are not getting it perfectly lined up. So it is off center just ever so slightly.
If you have enough bowl thickness. You can keep going till you get a good foot under it.
Of course if you are way off, your bowl would look to sit crooked. But it looks to be off just a little bit.
Probably not notice it at all.
Cole jaws help to reduce the guess work.

-- John

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Karda

3353 posts in 1767 days


#4 posted 07-19-2021 11:06 PM

thanks John

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Lazyman

7801 posts in 2600 days


#5 posted 07-20-2021 01:26 AM

Yep, cole Jaws or a Longworth chuck will help a lot with that. One other option is to mount a plywood disk that you can use for your jam chuck. That will give you a flat surface to press against instead of trying to get it perfectly centered and flat on a domed one. You can mount the disk on a faceplate but if you have a chuck, you can mount a attach a round block, glued and screwed to the disk, that you can mount in your scroll chuck. It sound like you may have have a 1” 8TPI tap so you can instead tap treads in the block so that you can mount the disk directly to your spindle. Glue some rubber to the face to help prevent the bowl from slipping. You can use sandpaper instead of rubber but rubber will better protect the rim better.

BTW, there are some free instructions/plans out there for making your own Longworth chuck if you have a router.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View TDSpade's profile

TDSpade

139 posts in 3629 days


#6 posted 07-20-2021 06:03 AM

I rough turn bowls wet. And finish turning them dry. The bowl and it’s tenon dry, are out of round. Getting them to sit flat in the chuck is rare. After I finish turning the dry bowl, I remove bowl and chuck together, screw the chuck into a tail stock adapter, mount a home brew vacuum chuck, bring the bowl up to the vacuum chuck, and then remove the regular chuck from the tenon.

Now the tenon and the base of the bowl below the tenon in most cases is no longer flat to the bottom of the bowl. Like an off center turning.

So I leave plenty of wood to make the bottom flat. Or slightly con cave.

-- For every expert, there is an equal and opposite expert.

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Karda

3353 posts in 1767 days


#7 posted 07-20-2021 06:11 AM

ok thanks

View Nubsnstubs's profile

Nubsnstubs

1798 posts in 2943 days


#8 posted 07-20-2021 01:53 PM

Mike, show us all how you set up to remove the tenon. After that is shown, maybe you can get better answers. You have the tools necessary to do an excellent job on removing tenons.

What i see is the bowl rim might be warped a little and not sitting flat on whatever device you are using, causing the bottom to not be square to the spindle. Like Bigjohn stated, if you have the thickness, go ahead and finish it because from what I see there isn’t enough distortion to cause it to look tilted when sitting on a surface…........ Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

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Karda

3353 posts in 1767 days


#9 posted 07-20-2021 11:53 PM

I found a couple things wrong, the jam chuck threads are crooked but t it straighted as tightened down The wood is pine so might have moved some. Also i had padding a little on the face but it didn’t cove the whole face so the bowl could rock a little. I tossed that one, I also found that some of the gouging is cause by the corner of the bowl gouge wing. knowing that helps some but I still have a hard time with bottoms, I can’t cut smooth close to the center. What kind of picture do you want. I use what work for a jam chuck with tail stock. and tail stock stready when I get that far

#10 posted 07-24-2021 08:20 PM

I have a video for tenon removal. I couldn’t bring myself to watch it, it’s about four years ago and I’ve come a long way since, but you might get something out of it.
https://youtu.be/WyR4GRyQi0g

-- Living In The Woods Of Beautiful Bonney Lake, Washington

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Karda

3353 posts in 1767 days


#11 posted 07-24-2021 09:05 PM

Phil thats not a bad video. I don’t have the guts to remove a tenon as you do, besides minimum on my lath is 750 RPMs. I think a lot of my problem is bevel control, if I take care of that i won’t need to scrape away from the center. still working on the off center issue. thanks for the video

View MrUnix's profile

MrUnix

8748 posts in 3412 days


#12 posted 07-24-2021 09:25 PM

Pretty much the way I do most of mine as well, except I will only go to the point right before ‘separation’ – that is, I will leave the smallest V shaped wedge possible, and then remove it off the lathe with a chisel or sometimes it will just snap off. Speed shouldn’t be much of a concern either. That was how I did it using my old Delta which had a minimum speed of 900 rpm.

Trick is getting it well centered, so you need to leave the initial center point on the tenon, and align with the jam chuck as shown in the video. As long as it’s balanced, it will be just fine and you can get down to a pretty small nub without much fear.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Karda

3353 posts in 1767 days


#13 posted 07-24-2021 09:53 PM

I’ll try that next time

View Phil32's profile

Phil32

1558 posts in 1116 days


#14 posted 07-24-2021 10:27 PM

Another thought: You might switch to using a recess (mortise) for holding bowls in your chuck. I turned the recess on this walnut bowl while holding the blank between centers. After turning the bowl, I turned a plug (base) to fill the recess.

https://www.lumberjocks.com/projects/408564

-- You know, this site doesn't require woodworking skills, but you should know how to write.

View Nubsnstubs's profile

Nubsnstubs

1798 posts in 2943 days


#15 posted 07-25-2021 12:00 AM

Mike, why is this starting to be a problem for you? You have the Tail Stock Steady and you have gotten instruction from me on tenon removal. The only thing I can think of is you don’t have enough bottom thickness and you are worried about punching through.

I’m going to head up to massatwoshiets in mid September. If you’re up for a meet up, I would gladly go out of my way a little bit to help you out some. After all, the best instruction is personal instruction rather than reading a bunch of words and then trying to do what the words say. Are you up for that????? ........... Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

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