Stripping paint from chairs – chair 2

A few weeks ago I bought a table and 4 chairs from someone at work. A bargain at 30 quid. I wrote before that I decided to refurbish the chairs from their black painted look, back to a natural wood finish.

With the first chair I tried a couple of approaches to stripping off the black paint. First I tried a hot air gun. Which was not terribly effective. So I moved on to paint stripper and wire wool.

By the end of the first chair I was getting the hang of the paint stripper approach. However it was still a pretty messy and slow process. And I was not particularly looking forward to getting the remaining 3 chairs complete.

Whilst in France I chatted to Kat’s dad about the job and he suggested a different approach. He pointed me at a set of nylon brushes that he had bought from screwfix. The go in your drill and are ideal for removing finishes. He’d used his to strip varnish, but the same should work for paint.

Given that they were not terribly expensive I ordered a set (and a trade pack of screws which always come in handy).

Co-incidentally I was browsing the forsale forum at work shortly after and I saw someone selling a DeWalt drill driver with 2 batteries and a 1 hour quick charge. Given that my now pretty old Bosch drill/driver has been struggling with failing batteries for a while I decided 40 pounds for a nearly new DeWalt was to good of a deal to pass up.

And so armed with new nylon brushes and a new drill I set to work on a patch of the second chair. And immediately I could tell this was going to be much easier than paint stripper.

It’s not trivially easy, but it is probably about as easy as paint stripping is going to get. The brishes do a good job of rubbing away the paint without doing too much to the underlying wood. Though you do have to be careful not to apply too much pressure.
Of course cordless drill/drivers are not really intended for continuous use, and the battery quickly drained.

No matter, I have a corded drill with a flexible shaft which I use for sanding and buffing things on the lathe. I use it this way because the switch broke some time ago, and once switched on at the main the drill is always on, until you switch it off at the mains. Not ideal for a drill, but fine for this kind of task.
Normallyit hangs from a screw next to the lathe. So I made up a quick wooden mount that it could rest in whilst I worked on the chair. ( I love my bandsaw, as it made doing that a 5 minute job rather than a long winded process)

Properly armed with a drill in a wooden support, and the my nylon brushes in the flexible shaft I set to work properly. And boy does it make short work of paint removal. It does generate a lot of dust which is the paint coming off. But it leaves the wood surface nice and clean ready for a final sand.

A couple of things too note if you consider doing this. Using drills with broken switches is not recommended. And you really do want a secure mount to hold it during this kind of use. The torque bring applied to the brushes can, under load end up applying to the drill. I had mind skip out of it’s resting place.

And more importantly, drills aren’t really designed for continuous use. They are designed for bursts of work, followed by rest. Using it like this made my drill hot. REALLY hot. I made a conscious effort to stop at regular intervals and allow the drill to cool. Yes this means the job elapsed time still takes a long time. But I’m happy that the amount of time I’m spending doing the paint stripping is much less.

I considered removing the motor from the drill housing and setting it up with some heat sinks. But decided that this way lies death from electrocution or fire. Better to just not forget it gets hot and compensate with breaks.

The spindles on the chair are a little more fiddly than the large flat areas, as you’d expect, but the nylon brush set comes with a couple of different shapes, and I have been making satisfactory progress with the narrow disc shaped brush.
I’ve not yet finished the second chair, but hope to do so this afternoon. And I’m a little happier at the prospect of getting the remaining 2 chairs done with the nylon brushes than I was with paint stripper.

The only problem I see is that I’m wearing through the main nylon bush pretty fast. At the rate I’m going I may need on per chair! which works out about 3.50 per chair if I don’t include the cost of delivery. that’s not too exessive, but deffinately a factor to consider.

Streptohedrons

A couple of months ago David Springett came to the Hampshire woodturners monthly meeting and gave a demonstration. Amongst the things he demonstrated were what he called ’streptohedrons’
I wrote about them at the time, as I was inspired a great deal by his demonstration. They are cool because the shapes you achieve are interesting and complex, but the method is relatively simple to understand.

You take 2 pieces of wood of the same size, with nice flat square faces and glue them together with a piece of newspaper in between. This is a paper join. You then mount the piece between centres along the glue join, being careful that you don’t just split the piece along the join when mounting it.

Then turn a shape in this piece. The only important thing is that what ever shape you turn you need to control what the cross section through that paper join looks like. It must have rotational symmetry. In its most simple form you turn a cone. A cone has a triangular cross section, and turned correctly, that triangle can be made to be an equilateral triangle and hence have rotational symmetry.
The cool thing is that the principal applies to any shape you can think of that has rotational symmetry.

Having been inspired by the theory I decided to have a go. The first challenge is actually getting two blocks with flat surfaces that will produce a nice flat join. David said that for this you really want a planer-thicknesser that can just give you a smooth flat surface to work with. Unfortunately these are very expensive, and I don’t have one.

What I do have is a bench belt and disc sander. And the belt sander does a reasonable job of getting a flat smooth surface. Though it is pretty hard to actually get it flat over a large piece. However having done the best I could I set about gluing the two pieces together. Unfortunately I didn’t have any news paper, and resorted to using a piece from the back on an envelope. This was not a good idea.

Once it had dried I mounted it on the lathe and set to work turning a cone shape. Just as I was starting to form the shape it PINGED into two flying pieces. (Always wear your face mask!)
It seems that paper from the back of an envelope is too thick, and did not help form a strong enough join.

Fortunately every Thursday I get a free paper delivered which normally goes straight in the recycling. This time I saved some, and started again.

This time I turned the glued up block down to a cylinder, measured the diameter and set to work on the maths. Another thing I love about this (because I’m a geek) is that it requires some Pythagoras’ theorem. And this means I can hark back to the glory days of GCSE mathematics when I was actually good at it. Before the rude awakening that was A-level maths. Who needs to know areas under graphs anyway? You can’t use that in wood turning.

It would probably have been easier to figure out the nearest whole numbers that I could work with. But I figured I’d make the biggest thing I could in the diameter. All of this good maths just to figure out how tall to make the cone.
With that established and marked, all you have to do is turn a straight line between the bottom max diameter and the top at which you should reach a point.

I discovered at this point that I had not been sufficiently careful about lining up my centre points on the glue join, and the tip of my cone was slightly into one side and not the other.

However the magic of sanding allowed this to turn into an acceptable streptohedron anyway

They make quite cool things for just fiddling with. I have this on my desk at work. Though David demonstrated techniques for hollowing them out to make little boxes, held together by rare earth magnets.

Having mastered the basic shape, I decided to go for something more complicated. In this case an octagon, which is turned as a sort of barrel shape.

This involved more maths. But really the same sort of thing. This time I decided it was easier to pick a starting edge size, and figure out if the cylinder I had was large enough. I tried a couple of different starting numbers until I found the largest that would fit in the diameter I had. I’m sure there are simpler ways to figure it out, but I couldn’t be bothered to go looking them up.

Having split it, this shape actually has two positions it could be re-joined at that result in different shapes.
This first is this

Which is pretty cool, but I preferred the second option

Which is the one I glued it as. Again once you get to this kind of shape, the idea of using small rare earth magnets is a good one, because then you can rotate to any of the alignments you like, rather than fixing one forever.

I think next time I shall try one of the harder ’star’ cross section pieces, that give pronounced spirals when formed as streptoheadrons. Or possibly have a go at hollowing out one of these shapes to make a small box. Not sure what you could put in such a box, but I guess the interesting part is the challenge of making it.

DIY lathe dust extractor hood

Last year I bought myself a serious dust extractor for use in the workshop. It has a huge dust collection bag and a 100mm hose.
I have it sat between my bandsaw and my lathe. The bandsaw has a specific dust port for connecting this type of extractor to which makes life easy. The lathe on the other hand is not so easy.

Basically I set it up with some garden wire providing a wire loop hanging off the bed bars, which I could hang the hose end in, which left it pointing vaguely where I was working. Whilst this seems fairly rubbish, the extractor is powerful enough that it was still effective at sucking up all the dust from sanding etc.

Although it has been effective, it was not really a satisfactory solution. The hose gets in the way, and often wound up not really pointing where I wanted it.

I looked around for ideas for dust collection hoods that would provide a more sophisticated solution. I found generic dust hoods for connection to 100mm hoses, but they seem to be fairly expensive for a shaped bit of plastic, which I’d still need to mount in something.

Having not really found anything that was quite what I wanted, and certainly nothing in a ’sensible’ price range. I decided to make my own.

So I hunted around my garage to look at what I had that might work as materials for this project. I quickly found a piece of plywood, about 5mm that looked like it would fit the bill. I also had a suitable size stick of something like pine, that was already planed and squared that looked good for a support baton which would get bolted to the bed bars.

The top of the plywood already had a big circle cut out from a previous project, and I decided that I could use that arc cut out of the headstock end, and just cut another section to the same dimensions for the other end. It has to be said I didn’t really bother to stop and figure out dimensions. I probably should of, but I basically went on what looked right, and I could keep sizing things up against the lathe to get a good idea.

Once again I really appreciated my bandsaw for making this project pretty trivial, it was very quick to cut up sections to size. Once I had the two end sections I decided to cut an angle on what would be the back top corner. And rather than measure to get it right on both ends, I just cut them both at once. For an exact match.

Then I just set the fence width to match the length from bottom corner to the corner of the diagonal cut, in order to cut the width of board for the back, and similarly set the fence for the angled top section. At this point I’d not settled on how wide I’d make the whole assembly, I basically set the ends on the lath to get a reasonable idea of what I wanted, and just cut both the back and top boards to match.

The idea was to just nail the left hand side to the pine stick which would have a channel drilled out so that it could be bolted to the bed bars just like my tool rest. Again I didn’t really measure, I just set it against the lathe to get an idea for how long to make the channel to get the range of movement I wanted.

I cut another piece of the pine to the same length for the right hand panel to nail to, and decided I’d just connect the rest with hot melt glue. Since it would be fast.

First things first I needed to cut out a channel in the right hand side that would allow my live centre tail stock to pass through, in this way I should be able to set the hood over at least the end of what ever I work on. If I have to work on something long enough that this end needs to be as wide open as the left hand side, I may adjust it then. For the moment I’d rather keep it as enclosed as possible,

This picture just showed me sizing it up against the tailstock to make sure everything was going to fit.

So now for the more complicated bit. Obviously I need some way for the hose to attached to this contraption. My idea was to make a ring that I would glue to the back board, which the hose would fit snugly over. For this I found myself a piece of MDF glued up to a block thickness that would give enough purchase for the end of the hose. Basically my hose has a few plastic guards that form a cross in the hoseway to stop big items getting sucked into the mechanism. These where set about an inch and a half back from the end of the hose, so I got a block of mdf about that thick to give it maximum interlocking space.
As it happened I had a lump of MDF laying around already glued into a block of just the right size. So I didn’t need to wait for any glue to dry. ( This is why I don’t throw anything away!)

Having got the block, I mounted it on the lath and turned it down to the correct diameter.

Here I’m checking it against the hose itself, you can see the plastic guards I was talking about.

Now all I had to do was hollow through it to form a ring. I wanted to leave enough wood to make it a pretty solid ring. I would after all be connecting and disconnecting the hose as I use it with other machines, so I want it to survive. But at the same time I’m conscious of the fact that these kinds of extractors are not designed to have their airways reduced. They lose suction, since it’s more about high volume of air, not high pressure of air. Which is the main difference between one of these and a regular ‘vac’
Anyhow I once again settled on a ‘by eye’ feel for what would work and set to hollowing

And once I was happy with the ring shape, I parted it off and was left with a nice neat MDF ring of just the right size.

With the ring formed I placed it roughly where I wanted it on the backboard, and drew a circle for it’s internal diameter. Which I then needed to cut out of the board. For this I decided to just use my drill press to drill a bunch of holes all the way round the circle, then just use a chisel to cut the connecting bits

This wasn’t terribly neat, but it was fast and easy. I just couldn’t be bothered to get my jigsaw out, even though it might have made a neater hole. I just used a bit of rough sandpaper to smooth the worse of the rough edges and plowed on.

I glued the ring in place at around this hole. I had actually tapered the ring slightly so that the fit on the hose would get tighter as it went over, So I was careful at this stage to glue the wider edge to the board.

With that clamped in place, I decided I was too impatient to really wait several hours for the wood glue to dry, so I got out my hot melt glue gun and set it warming up.

This is the first time I’ve really used my glue gun for a project like this. I’ve read variously of them being used to form quick glue chucks which can then be re-heated to remove later, and so I figured it would be easily strong enough for my needs.

I added a little hot glue around the ring against the board. And let it dry whilst I got together the other panels.

Hot melt glue made this bit really fast and easy, just run a line of glue along the joins and hold for a few seconds before moving on.
And before you know it, you’ve got a dust extractor hood!

I think it’s taken me almost as long to write about this as it took me to get this far actually making it. It really was very quick to put together. And I was keen to put it in place and have a go.
I had ummed and ahhed about putting a ‘floor’ in place, vs just leaving it open. In the end I decided to cut a panel to size, but not glue it in initially to see how I got on.

This is it in place, it only gets bolted on the left hand side, the right hand is just resting on the bed bars.

Next I attached the hose to the back, which was a bit fiddly because it’s quite a tight space, and the host isn’t all that flexible for tight 90 degree bends.

With everything in place I decided it was time to give it a whirl. And so I switched everything on and attempted to sand the piece of mdf still on the lathe. This worked great! I could just make out a steady stream of fine mdf dust going straight into the extractor. Wanting a more visually obvious demonstration I decided I’d just a tool to see how it handled larger bits being cut off.

At this point I discovered the first thing I’d not taken into account. I went to move the tool rest into place, and realised it hit the bottom of the back board. So I couldn’t get the tool rest in position properly. I was now glad I had not glued the ‘floor’ in place, and the adjustments became obvious.
Cut a section out of the bottom of the back board, big enough to allow the tool rest clearance to move around. Then set the ‘floor’ at an angle up towards the hole.

Some quick adjustments later and I ended up with what is now a finished extractor hood.

I’ve now had it in use a few times, and love it. It does a great job of sucking up a lot of the debris coming off the lathe. Obviously the large chunks tend to go all over, but mostly it’s the dust and finer pieces I’m interested in capturing, and it does this without the hose getting in my way.

The couple of issues I have is that it’s a bit slow to attached and remove, and since it only bolts on one side, the hose occasionally pulls it enough to twist the whole thing. I’m not sure if I will do something about that or just live with it. If I add another bolt it will just get even slower to setup and take down.

Generally this was a great little project. Very quick to put together and very cheap, given I used materials I already had laying around as effectively scrap. And I hope that it will help my dust extractor be even more effective when I’m using the lathe, which can only be a good thing.