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Forum topic by Karda posted 04-23-2019 11:51 PM 525 views 0 times favorited 24 replies Add to Favorites Watch
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Karda

1485 posts in 916 days


04-23-2019 11:51 PM

Hi, I got a small maple crotch, it measures at the end where I would put the tenon for a hollow form 4” by 3.75”. the minimum tenon my chuck will hold 1.75 ”. any idea how I can mount this to hollow it out. Any ideas on shape. Thanks Mike


24 replies so far

View Wildwood's profile

Wildwood

2622 posts in 2496 days


#1 posted 04-24-2019 11:36 AM

Might think about how much of that blank can actually turn. Start out with measuring and marking with pencil!
I might turn a paper clip/pencil holder, ornament either round (hollowed out) or bell.

Hard to say because don’t know what other turning tools you have other than a bowl gouge. A parting tool would make short work of turning a tenon to size to fit your chuck. Have used my 1/2” skew to turn tenons too. Have seen guy use modified screw driver and 1/4” wood chisel to turn tenons but don’t recommend that.

If only had one parting tool or going to buy one would recommend an inexpensive diamond parting tool.

https://www.pennstateind.com/store/LX430.html

Once get the piece mounted in your chuck have to measure how deep can go without hitting the chuck re-measuring and marking that with pencil line.

Next figure whether want to work on outside or inside first. I like to work the outside first! I want to turn a pleasing form, and something that small will start off turning another tenon maybe 1/2” wide and deep which will allow my gouge to sweep down to new tenon. Once finish turning/, sanding, & finishing out/inside will reverse mount blank in chuch and turn away second tenon.

-- Bill

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Karda

1485 posts in 916 days


#2 posted 04-24-2019 05:18 PM

I am not asking how to make a tenon that is not a problem. The problem is there might not be room for the smallest tenon I can make and still have it seat properly in the chuck. This piece I may not finnish but I have run into the no room for a chuck problem before and was wondering if there was an alternative short of a smaller set of jaws

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Wildwood

2622 posts in 2496 days


#3 posted 04-25-2019 11:24 AM

Sorry post doesn’t help good luck with it!

-- Bill

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Nubsnstubs

1534 posts in 2092 days


#4 posted 04-25-2019 04:00 PM

Mike, I don’t see a problem. I guess your crotch is 4” OD x 3 3/4” long. If these are reversed, still no problem. Turn a tenon on your crotch, and reverse it and finished the job…. Problem solved. Turn the tenon to 2 1/4”. In order to get the tenon length needed because it’s round where the live center makes contact, you can leave a nub up to 3/4”OD where the live center makes contact. When the tenon is done, the nub usually clears the center hole in the chuck, so it’s not an issue.

I make all my tenons for the 50mm jaws at 2 1/4” OD x 1/4” long. I had too many of those fully round jaw wrap arounds break on me in the past. Since late 2010, I went to the 2 1/4” tenons, and the only one to break were the burls that I clamp onto. ............ Jerry (in Tucson)

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

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Jack Lewis

437 posts in 1440 days


#5 posted 04-25-2019 04:28 PM



Mike, I don t see a problem. I guess your crotch is 4” OD x 3 3/4” long. If these are reversed, still no problem. Turn a tenon on your crotch, and reverse it and finished the job…. Problem solved. Turn the tenon to 2 1/4”. In order to get the tenon length needed because it s round where the live center makes contact, you can leave a nub up to 3/4”OD where the live center makes contact. When the tenon is done, the nub usually clears the center hole in the chuck, so it s not an issue.

I make all my tenons for the 50mm jaws at 2 1/4” OD x 1/4” long. I had too many of those fully round jaw wrap arounds break on me in the past. Since late 2010, I went to the 2 1/4” tenons, and the only one to break were the burls that I clamp onto. ............ Jerry (in Tucson)

- Nubsnstubs


Jerry; You go against the idea and “advise of the experts” to a tenon being JUST slightly larger than your chuck jaws? The jaw points are all that hold in your philosophy not that I disagree! I have begun, where possible, to cut a tenon and socket and use the other to recenter if one gets damaged.

-- "PLUMBER'S BUTT! Get over it, everybody has one"

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Karda

1485 posts in 916 days


#6 posted 04-25-2019 05:21 PM

sorry the 4” OD x 3 3/4” are the measurements of the end where the tenon will be. I flattened the bottom and there is room for a tenon. I was wonder what you would do if it was to small for a tenon

View HokieKen's profile

HokieKen

9240 posts in 1500 days


#7 posted 04-25-2019 05:29 PM

If it’s too small for a tenon that fits the jaws you have you can glue a sacrificial block to the end and then turn your tenon onto that. I’d probably just get another set of jaws for the chuck if that’s a situation you anticipate.

-- Kenny, SW VA, Go Hokies!!!

View Phil32's profile

Phil32

534 posts in 265 days


#8 posted 04-25-2019 06:04 PM

I usually prefer to make a recess (mortise) to mount to my chuck. This can be turned at the tailstock center, leaving a minimal nubbin of wood until the final moment. This recess can then be filled with a separately turned baseplate.

(photos to be added)

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

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Karda

1485 posts in 916 days


#9 posted 04-25-2019 06:44 PM

yea I prefer a mortise over a tenon but you need more room for a mortise. I have used glue blocks for that situation but that not possible on green wood. I wa looking at jaws and there were so many different kinds I didn’t know what to get, besides they are more expensive than I can afford for an occasional use

View OSU55's profile

OSU55

2250 posts in 2351 days


#10 posted 04-25-2019 07:49 PM

On that size of piece it may be better to go with a glue block as it will increase the size of usable wood. I use that approach on smaller pieces. Depending on what you decide to make, if the block end needs to be small, say 1-1/2”, turn that end down between centers then mount the block. You dont want to turn down the OD of the glue joint much as a properly made one is only 1/4-3/8” wide.

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Karda

1485 posts in 916 days


#11 posted 04-25-2019 08:24 PM

can’t use a glue block on green wood

View Phil32's profile

Phil32

534 posts in 265 days


#12 posted 04-25-2019 08:38 PM



yea I prefer a mortise over a tenon but you need more room for a mortise. I have used glue blocks for that situation but that not possible on green wood. I wa looking at jaws and there were so many different kinds I didn t know what to get, besides they are more expensive than I can afford for an occasional use

- Karda

It’s about the same, but if you make a mortise you retain the full length of your blank. The loss of length (if any) in inside your piece.

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View LeeMills's profile

LeeMills

660 posts in 1663 days


#13 posted 04-25-2019 10:35 PM



can t use a glue block on green wood

Look up Lyle Jamieson on youtube. He has a couple of videos just on glue blocks. He is a professional turner and states he never uses a chuck. You can use a glue block with green wood if you use CA glue (thick normally used).

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

View Nubsnstubs's profile

Nubsnstubs

1534 posts in 2092 days


#14 posted 04-25-2019 11:03 PM

I don’t see a problem. I guess you crotch is 4” OD x 3 3/4” long. If these are reversed, still no problem. Turn a tenon on your crotch, and reverse it and finished the job…. Problem solved. Turn the tenon to 2 1/4”. In order to get the tenon length needed because it’s round where the live center makes contact, you can leave a nub up to 3/4”OD where the live center makes contact. When the tenon is done, the nub usually clears the center hole in the chuck, so it’s not an issue.

I make all my tenons for the 50mm jaws at 2 1/4” OD x 1/4” long. I had too many of those fully round jaw wrap arounds break on me in the past. Since late 2010, I went to the 2 1/4” tenons, and the only one to break were the burls that I clamp onto. ............ Jerry (in Tucson)

Mike, I don t see a problem. I guess your crotch is 4” OD x 3 3/4” long. If these are reversed, still no problem. Turn a tenon on your crotch, and reverse it and finished the job…. Problem solved. Turn the tenon to 2 1/4”. In order to get the tenon length needed because it s round where the live center makes contact, you can leave a nub up to 3/4”OD where the live center makes contact. When the tenon is done, the nub usually clears the center hole in the chuck, so it s not an issue.

I make all my tenons for the 50mm jaws at 2 1/4” OD x 1/4” long. I had too many of those fully round jaw wrap arounds break on me in the past. Since late 2010, I went to the 2 1/4” tenons, and the only one to break were the burls that I clamp onto. ............ Jerry (in Tucson)

- Nubsnstubs

Jerry; You go against the idea and “advise of the experts” to a tenon being JUST slightly larger than your chuck jaws? The jaw points are all that hold in your philosophy not that I disagree! I have begun, where possible, to cut a tenon and socket and use the other to recenter if one gets damaged.

- Jack Lewis


Jack, not looking for an argument. As stated, before 2010, I followed the manufacturers and xperts guidelines of making tenons the size where the jaws are about true round. From what I can recall, I believe a 50 mm jaw set will accept a tenon at 1 13/16 – 7/8” and close with a good round clamping action. I was losing one out of 20 pieces.. Not one of them came out of the jaws. They all broke at the tenon and bottom of the piece. I started making my tenons at 2 1/4” in 2010. Since that time, I might have lost one or two pieces from the chuck not holding because of not tightening it. One launch might be on youtube in Nubsnstubs’ channel. You will have to hunt for it. The other, who knows??

My point is, my entire life, I was always instructed or told and practiced that the more surface area you have to hold something, the more secure it is. That means the larger the tenon, the stronger it is. A 2 1/4” tenon has 7 1/16 square inches” surface area, where a 1 13/16” tenon only has 5 11/16 square inches of surface area. Another thing I mentioned in another chuck thread was, “If the jaws won’t hold as securely on the larger opening of the jaws, WHY do the chuck manufacturers make the chucks and jaws open larger than what they and the xperts consider safe???? It would be real easy for them to put a stop in the scroll to keep from going any larger than round.

I used to subscribe to an “xpert’s” youtube channel once. He was turning a hollow form that would net about a 7” finished form. Somewhere in the video, he mentioned he didn’t use chucks because they wouldn’t hold what he was making. From that point on, I think this particular xpert is full of it. I learn on my own and not readily jump in and do it this way because an xpert said so.

Mike, you do what you think is the right thing to do. It doesn’t matter whether you make a tenon or recess. The bottom thickness will be the same no matter whether it is a tenon or recess. You will not sacrifice any thickness. As far as the glue block, wet wood/dry wood. The glue will work. I would give it about a week to cure rather than the couple hours glue manufacturers suggest, but for best results, recommend 24 hours. .......... Jerry (in Tucson)

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

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Karda

1485 posts in 916 days


#15 posted 04-26-2019 12:12 AM

thanks lee I’ll take a look

showing 1 through 15 of 24 replies

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