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How to get a tightly fitting lid

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drillbit

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I've watched every video I can find on box turning. Have also made a good few now, and attempted as many again.

The only thing I cannot achieve is a permanent snug fit.

I've managed to get a nice snug fit on a couple of boxes. But two days later the lid seems to have shrunk and the fit is completely loose. This was with bought blanks so I was surprised at the movement.

Somany videos show people getting such a good fit that they can push the lid back on to chuck it. I find there is only a nanometer difference between being loose, or so tight the lid or box splits, depending on which is the female half.

Is it not possible to get a lasting tight fit on a simple box by just having a spigot on the lid fitting into the body of the box? Or is there a technique or trick to make it stay snug permanently?

Any tips greatly appreciated..
 

cornucopia

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there are a few things going on here which will affect the fit:

most importantly you must rough turn the timber and leave it in your house to settle before making the final box. no matter where the timber is from or how dry you think it is- if you don’t do this the fit will always change.

the female tenon whether on the base or lid must be parallel- if it’s not it will be very difficult to get any sort of good fit.

on the lid which becomes loose after two days: if you rotate the lid on the base you will find that every 1/4 turn its loose and every 1/4 turn its tight- that proves my first point and tells you the timber wasn’t stable as its lost its concentricity and gone slightly oval.
 

jumps

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drillbit":hjz7r9qd said:
Or is there a technique or trick to make it stay snug permanently?

Any tips greatly appreciated..
Use a thread........ #-o
 

drillbit

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Cornucopia - thanks for that. So when you say 'rough turn' what does that mean? Do you mean just roughing to a cylinder and actually making the whole box when it is dry..or actually hollowing out and shaping...leaving just the tenon to finish off later snugly?

And also, how long are we talking about? Days...months?

You are dead right about the oval shape - that's exactly what happened but by the second day it was round again..and too small.

@jumps and mike s - that's cheating.... :)
 

bobham

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I have been having good luck with a technique I learned from a Jimmy Clewes video. I make the spigot with a very slight bulge in the middle. As Jimmy says in the video, "its not a measurement, its a feeling". The recess for the spigot to fit into is straight sided.

I usually put the spigot on the box and the lid fits over it, rather than the other way around, but I don't see where that would make any difference. I have found that if I make a really tight fit (to jam chuck the lid) before I hollow the box then the fit is almost always a bit looser after the box is hollowed.

I use a sharp skew chisel as a negative rake scraper for the fitting of the spigot to the recess. It allows taking off very small amounts to achieve a good fit. Avoid sanding the sides of the spigot or the sides of the recess because you really can't tell how much you are taking off with sandpaper and it will remove more from softer areas than harder areas so the parts won't be truly round.

Good Luck!
Bob
 

cornucopia

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by rough turn I mean- turn the blank to a cylinder and part the lid from the base- hollow out the base and lid but leave the wall thickness extra thick to allow for movement. depending on the wood type and how wet it is will determine how long you have to wait, if it very wet then a year or two- if it feels dry then maybe on 3-6 months. but the most important thing is when the blanks are ready to turn they must have been stabilized in your house, the roughed out blank is then brought into the workshop on the day you make them and brought back into the house completed.
 

drillbit

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Thanks Corucopia. Definitely not for the impatient then (eg. me) !!

I actually use a room in my house as a workshop, so will that mean if I keep the blanks in my workshop for 3-6 months they will already be at the right readiness to some extent?

Also - does this mean that if I get them to be a perfect fit for my house...and then give them to someone else...their house might be different, and the wood might move again to make them too big a fit? Or would the finishing 'seal' the wood from moving?
 

tekno.mage

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Getting a permanent good fit on a box with a push fit lid can be tricky. As Cornucopia says, it is important to rough turn the box and let it "rest" for a long as possible before finish turning - and it should ideally be rested in the environment it will eventually be kept when it is finished (ie probably a centrally heated house).

This is what I do when I make boxes with push fit lids....

1. Rough turn the blank - which means make it into a cylinder, cut chucking spigots on either end, part off lid from base, then rough hollow the two parts - do not leave the walls too thick at this stage, but leave enough material for trueing up should the blank go hollow (this is less likely with a dry blank, very likely with a wet log!).

2. Tape the two parts together and bring indoors. Weigh the parts and note the weight on them. If the wood was already "dry" I then put the rough turned blank in the airing cupboard (to simulate warm, dry centrally heated house - which mine isn't) and leave it there until the weight stops dropping. The wood is then very, very dry.

3. Take the blanks out to the workshop and finish the box - do not leaave the blank in the workshop unless you are working on it (ie bring it indoors between stages if you don't have time to finish it all in one go.)

4. Actually fitting the lid - (for an over fitting lid). I finish and sand the inside of the lid - making sure the part where the flange of the base will fit is absolutely parallel. Then I mount the base on the lathe and finish & sand the inside of the box - the reason for this is because finishing the inside *may* cause further movement of the wood and I want that out the way before fitting the lid.

Next, I cut the flange for the lid. Initially this is cut as a slight taper (so the lid goes on part way and leaves a witness mark.) Then the flange is then cut parallel to the size left by the witness mark. I tend to use a small parting tool for this, but angled so it's actually cutting like a skew chisel and leaves a nice clean surface that would need no sanding. The lid should now fit VERY tightly - in engineering terms "a tight fit". I now finish & sand the outside of the box and the top of the lid (with tailstock support until I absoluely have to remove it.) Which leaves a finished, smoothly sanded box with the lid stuck on really tight - I find wearing a leather glove helps grip the lid so I can now remove it to finally fit the lid. Again, using a small parting tool as a skew, just kiss the surface of the wood and keep stopping and checking the lid fit as you go until you are happy with it. At this stage you could also shape the flange so it is very slightly barrel shaped to get a nice suction fit - Richard Raffan's book on making boxes goes into flange shapes in great detail, BTW and I found it really useful when I first started making them.

5. Having got the box to this stage - I take it off the lathe and back in doors - with the chucking spigot still on the base and leave for another couple of days. If the lid goes too tight - it can be remounted and dressed very carefully with fine sandpaper (400 grit or finer) until it fits again. If it goes the other way you can sometimes recover a slightly loose lid by applying an extra coat or two of whatever finish you use around the flange area. I use hardwax oil on all my boxes which is applied off the lathe so this is not a problem.

6. Some finishes and colouring techniques will affect the fit of the lid - any finish that raises the grain of the wood will make the lid just a bit tighter. Wax on the flange may make a tight lid a bit easier to get on or off. Adding texture bands to lid and base makes a box easier to grip for removal of tight lids.

7. Some woods move more than others which can be tricky for boxes. I've found that walnut hardly moves at all, whereas boxwood moves a lot more than you would expect!

8. Large boxes (3" or more in diameter) cause more problems with movement than small boxes - large boxes with tight fitting lids can be a nuisance to open - I usually make large boxes with looser fitting lids, or with threaded lids.

9. Make sure any finishes you use have cured properly before leaving the box with it's lid on. Leave at least 24 hours to be sure. Acrylic finishes may "stick" on mating parts if not properly cured, even though the finish feels "dry" to the touch.
 

drillbit

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Kym - Wow. That is a really comprehensive guide. Thanks very much. I have to admit I find the thought that it will take such a long time to complete is frustrating for me - I am always impatient to finish - but I will just have to learn to be patient, and have more than one box on the go.
 

Woodchips2

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drillbit":ze9w4p94 said:
Kym - Wow. That is a really comprehensive guide. Thanks very much. I have to admit I find the thought that it will take such a long time to complete is frustrating for me - I am always impatient to finish - but I will just have to learn to be patient, and have more than one box on the go.
Or turn them with a looser fit! As you get older and don't have the strength to remove a tight fitting lid the box becomes impractical. :(

Regards Keith
 
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