Last week was the July meeting of the Hampshire wood turners association. I've already written a mini report for the Hampshire woodturners new websiteThis is not yet the official website, but I've been working on them to move. Since I believe that a wordpress blog is much easier to manage than their current website. If all goes to plan they will redirect their hostname to the new site, and I can help them create content there.
However I still wanted to write up my own impressions of the meeting, and keep them separate from the 'official' writeup.
This month Mark Hancock came to demonstrate what he termed a 'rocking vessel' What this actually means is a hollow form, with no flat base. So rather than standing up in a conventional way, they roll around, or 'rock' to a natural resting point.
These are interesting, I'm not sure what I personally think about the particular design he showed us. I was interested in the methods that went into making it, but I don't think I actually liked the resulting object.
The texture on the outside is probably the thing I was most interested in. However before we got to that he shaped the outside profile down from a cylinder and then hollowed it.
Having seen a number of demonstrations now, there are certain things that are getting a little old, repeated information that everyone gives. Certainly I don't think they should stop giving it, after all I found the same information interesting the first time. But now I find I'm tuning out from certain bits of tips and advice that I've heard repeated often.
That said Mark had some useful points to make about the complicated terminology used in woodturning. The same things tend to get referred to in various ways by different people. Spindle turning, bowl turning, faceplate turning, end grain turning, etc etc. He pointed out that many of the terms dictate what you're turning. Instead he prefers to talk about all turning as one of 2 types. Parallel grain turning, where the wood grain runs parallel to the bed bars. And cross grain, where the grain runs at right angles to the bed bars. The methods of holding etc etc, are a different factor, but the thing you need to understand is the direction of grain and the implication that has for tool use.
One great tip that I pricked up my ears for, regarded putting a dead centre in the headstock inside when you attach a normal chuck. His reason for this was having once attached a large heavy piece to a headstock on a Record lathe, (same make as mine but a few models higher) and when he switched it on the weight simply crushed the mostly hollow spindle. Ouch. Repairs cost him 3 or 4 days of being unable to turn (which he did professionally) and a not insignificant sum. By putting a dead centre in the spindle, you effectively make it a solid bar. It had not occurred to me that it would fit, but given I have one, and it is basically useless for anything else. I shall try to get into the habbit. I don't think I'm in danger of turning anything that heavy. but better safe than sorry.
Something I noticed about this demo, as compared to last months. Was that nearly every part of it used a tool I don't have. Where as last months demo was mostly showing what you can achieve with simple tools and careful measurements. (Ok so they also indicated a need for a bench planer which is not a small requirement, but you could get by without)
This month though, hollowing was done with a special hollowing tool. It did make the job look easy, and he had a number of tips to provide. But I'm not about to go get myself a hollowing tool so...
One interesting tool use was to use a cabinet scraper to help get a good finish on the outside. He was able to use it freehand, and could do some final shaping with it to help him get the form he is looking for. Cabinet scrapers aren't too expensive and can easily be sharpened on a dry grinder. It was interesting to see a tool being used without a tool rest, but I guess the point is that you're taking very light cuts to get a better surface finish.
Then having used the hollowing tool to form coves at intervals on the outside (he could of used a spindle gouge etc, but since he had the hollower in his hand and it would do the job why not)
The result looked a little like a large honey stick thing. Like a bee hive or something.
Next he marked out parallel lines around the outside of the shape. Basically using the jaws for the chuck to give him 4 evenly spaced points, and drawing by eye along the length. Then, again by eye, drawing another 4 lines evenly spaced, each half way between the first 4.
He made a good point here, that accurate measurement was not necessary, in fact could be harmful to the overall effect. This is supposed to be an organic shape, so too much precision could make it seem machined.
Then for another fun tool, the mini arbortech. This is an attachment for an angle grinder (I've got an angle grinder so that's something) It extends out and provides a mount for a smaller cutting blade which is basically 8 chainsaw teeth in a circle. With this he could lock the vessel in place, and run the min chainsaw along the lines he had marked out, cross cutting the coves. To give the outside texture.
At this point I was wondering how you get back to a nice smooth finish, having a pretty rough cut with the arbortech. And the answer was to burn it!
Apparently it is a well known technique for treating wood, to scorch the outer layers black. This forms a hard outer surface which protects the body of the wood.
At this point another tool I don't have, a blow torch. Mark mentioned that you need a gas that burns as hot as you can. This allow you to scorch the outer layer quickly without causing heat checking in the wood. There are various blow torch types available, and he used mapgas (at least I think that's what he called it) it came in a yellow cylinder and he said you can get it in places like B&Q. This burns hotter than butane or propane, and whilst it is more expensive, you actually use less because it has effect quicker.
I didn't see this bit in action, because he went outside, away from smoke detectors. He did give some sensible safety tips for if you're doing this sort of thing. Get fireproof board to do it on. A welders glove to protect your hands, clear up any wood shavings that might catch. And do NOT use dust extractor either during or after. As there is a risk of pulling an ember into your dust extractor where upon hilarity will not ensue.
The burning process was followed up with using a stiff brush attachment on the which he held the wood against, this brushed off loose material, and gave the wood a tough sheen. Which would be good enough as a finish if you wanted.
But his last step was to use a rasp file to cut back areas that he wanted colour to take (apparently it doesn't stick to the ebonised smooth surface)
And so he brought into action another tool I don't have. An Airbrush attached to a compressor. HE had a duel action airbrush that let him control airflow by pressing down, and colour flow by pulling back on a little 'joystick' This looked pretty cool, and allowed him to layer on some colours into the groves of the surface.
Of course I cam away thinking...can I justify an arbortech? An air compressor? A funky hollowing tool? At the moment probably not. But maybe if I find other things that I could do with an air compressor, I might eventually get one. Or if I really want to get into hollow forms, a a nice hollowing tool may become a must.
Despite all the tools on show that I don't have. I found it an interesting demonstration, and it's always nice to see something quite different and unusual being made, to be inspired by different techniques and possibilities.