What size lead in twig pencil ? What grade?

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What size lead in twig pencil ? What grade?

Postby gavin » Wed Feb 01, 2012 10:53 pm

I have made twig pencils with 1.8 mm HB lead. These often snap as you push the lead in the twig. (But they were dead cheap on Ebay.)
I had better luck with Ryman's leads of 3 or so mm.

If you have made these yourself:
    What diameter do you recommend?
    What degree e.g. HB or 2B or 3H do you recommend?

They are really easy to make and even easier to sell at shows, so I'd like to get this right.
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Re: What size lead in twig pencil ? What grade?

Postby mstibs » Wed Feb 01, 2012 11:13 pm

I can only speak about the hardness degree. Having been taught technical drawing in vocational training as a mechanic 25 years ago, I'd recommend HB. If I remember right, it's a middle degree of hardness and most people will like how it draws.

H = hard ... 3H = bone hard. We used max. 2H for drawing fine lines e.g. for measurement lines. B = ballon = soft. The B or 2B leads wear out quite fast because of their softness.

The H degrees need much pressure to draw a thicker line to the paper and if it's a too hard lead and too thin paper, the pressure can easily destroy the paper, especially in young kids hands. If you go for HB, you have a nice degree of hardness for nearly every drawing situation.
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Re: What size lead in twig pencil ? What grade?

Postby goldsmithexile » Sun Feb 05, 2012 9:40 pm

I use a lot of different pencils. It depends on the ratio of clay to graphite used in the making. (b is mostly graphite, not much clay so it is soft and gives a dense black, h has much more clay, less graphite so it is harder and you dont get such a dense black line). Maybe you could make your own mix of clay and graphite? I am not sure if it has to be oven fired before it is put inside a wood barrel or twig. German lyra graphite is about the best
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Re: What size lead in twig pencil ? What grade?

Postby jrccaim » Wed Feb 08, 2012 5:21 am

As mstibs remarked, it depends on what you want to do with the pencil. If you intend to use it yourself, please follow mstibs recommendations; spot on. ( I, too, was taught mechanical drawing or draughting in UK-ese, 50 years ago, as an Engineering student.). But if you want to manufacture these things for sale, I'd suggest getting a big box of the cheapest, most unattractive ordinary lead pencils you can find. Deconstruct the pencils. Use the leads. Most people (your customers) don't know a number two lead from a chisel. It's what they are used to, after all. Novelty appeal is what will sell a pencil. Your customers will probably never even sharpen the thing :)
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Re: What size lead in twig pencil ? What grade?

Postby Davie Crockett » Wed Feb 08, 2012 3:50 pm

It seems that the majority of bulk suppliers use 2mm HB as standard 3B (Soft) is available as thicker cores 3mm-3.5mm. These come from China, with a minimum order of at least 1000pcs, some with 3000 and some with 12000. http://www.alibaba.com/showroom/hb-graphite-pencil-core.html (Google search Graphite pencil core)

I don't think I can use that many!

You can find stationers who supply 5-10 refill cores at a time for propelling pencils, but they are rarely of a greater diameter than .7mm and too fragile to insert into twigs.
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Re: What size lead in twig pencil ? What grade?

Postby jrccaim » Sun Feb 12, 2012 5:14 am

OK, here we need some definition. Gavin, what do you mean by a twig pencil? There are two possibilities. Option One, you buy or salvage a mechanical pencil meachanism and insert it in a twig. The mechanical works accept 0.5 - 1 mm leads, and as near as I can see, each mechanism accepts only one size. Mine are all 0.5mm but I have seen 0.7mm leads for sale (in supermarkets!) so I assume someone makes the mechanism for that size. One way to go, to be sure. Option Two is, you take a twig, drill a something-like-2-3 mm hole in it and insert a lead, possibly with some epoxy at the end. In other words replace the ugly ordinary lead pencil with something more natural. When I read your post I jumped to the conclusion that you meant option Two. Hence my suggestion of deconstructing an ordinary lead pencil. I think this is a great Crafts Faire project.
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Re: What size lead in twig pencil ? What grade?

Postby gavin » Sun Feb 12, 2012 11:18 pm

jrccaim wrote: Option Two is, you take a twig, drill a something-like-2-3 mm hole in it and insert a lead, possibly with some epoxy at the end. In other words replace the ugly ordinary lead pencil with something more natural. When I read your post I jumped to the conclusion that you meant option Two.

Yep , that's it. Hole in twig, push lead in. Hopefully without expoxy.
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Re: What size lead in twig pencil ? What grade?

Postby jrccaim » Mon Feb 13, 2012 5:43 am

gavin wrote:Yep , that's it. Hole in twig, push lead in. Hopefully without expoxy.


Ah, I jumped to the right conclusion! Pure accident. Reason I suggested epoxy is because I have lots of experience fittng cylinders to holes. Any drill bit will usually drill slightly oversize. In my experience the "slightly" is something like 0.1mm, maybe 0.2mm in wood. You want a "press fit" as machinists say. For that you need a smaller bit. For a 2mm lead, 1.8 or 1.9 is about right, but that gets you into fractional sizes. I happen to have a set of machinist's drill bits, 1mm to 6mm in 0.1 steps. They are not particularly expensive. Axminster's catalog [drool] is your friend there. But poor man's solution: drill to lead size and put a dab of epoxy or super-glue on the end of the lead. This will prevent the lead from rotating when the pencil is sharpened, or worse, from falling out.
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Re: What size lead in twig pencil ? What grade?

Postby jrccaim » Fri Feb 17, 2012 5:29 am

Once again, put my money where my keyboard is. So I deconstructed a piece of super-cheap lead pencil, and measured the lead carefully (with digital calipers BTW) 2.0 mm spot on. So I drilled 1.9, 2.0, 2.1 and 2.2 holes in a block of dry birch. It was a case of Goldilock's porridge. 2.0 too tight, 2.2 too loose, 2.1 "just right."

Ah, but there is more. So today I tried my hand at a twig pencil. Had a dry piece of lilac twig available. BTW I turned the lower end down on my tool-handle pole lathe, posted in another thread. OK. It is easy to drill a 2mm short hole, as long as the bit you have. hole. It is not so easy to drill a 2mm long hole. Immediate problem. The smaller the bit the shorter it is. My 2mm bit is about 35mm long. Can vary this by chucking, but only so much. Perhaps one can find a long (and how long is long?) 2mm bit somewhere; or perhaps I can find a longish piece of 2mm steel rod and make my own bit. Or even turn one down from something bigger. My Taig lathe will do that. Interesting problem. Since one is making twig pencils, one is driling out the pith, so extreme hardness of drill bit not much of a problem.

Amazing note: When I took the lead pencil apart, the wood was shrunk tight around the lead. Wonder how they did that. Maybe soak (or steam) the wood, drill the hole, insert lead, dry wood out. Shrinks when you dry it, wood does.
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Re: What size lead in twig pencil ? What grade?

Postby gavin » Fri Feb 17, 2012 7:50 am

jrccaim wrote:... It is easy to drill a 2mm short hole, as long as the bit you have. hole. It is not so easy to drill a 2mm long hole. ...

You seem to presume that the hole for the lead must go all the way up the pencil. Just 'cos those we buy from a stationer have long leads, I suggest the twig-lead need not be longer than 25 mm. Just make more pencils rather than fret about making a long 2 mm bit which will be more fragile as it gets longer. After all, the purpose of the pencil is to get folk to see how simple the process is - or to pay you money. They won't pay more for a lead that goes all the way. And they may think the long bit makes the process nasty and complicated.

Keep It Simple . By the tenor of your excellent posts on this board, I do not think you are stupid JR, so I definitely don't add the final 'S' to that well-known acronym.
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Re: What size lead in twig pencil ? What grade?

Postby jrccaim » Sat Feb 18, 2012 5:22 am

gavin wrote:
jrccaim wrote:... It is easy to drill a 2mm short hole, as long as the bit you have....

Keep It Simple . By the tenor of your excellent posts on this board, I do not think you are stupid JR, so I definitely don't add the final 'S' to that well-known acronym.


Oops. Yes, absolutely right. If a short 'ole will do the thing why worry? I got all caught up on the problem of drilling a long 2mm hole and overlooked the obvious :oops:
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Re: What size lead in twig pencil ? What grade?

Postby 1josephsutton » Mon Aug 14, 2017 11:21 am

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