A Driving Instructor's Blog

DIY

Here’s an update to my on going project (Part 1 here and here, Part 2 here) to build a kneeling chair .

Also take a look at the Part #3 Update here.

The diagram below – you can call it a blueprint or whatever (I make no claims in that area) – shows the holes and necessary cut outs for the support struts I am going to fabricate from the steel I purchased recently.

Kneeling Chair Parts - Drilled Holes And Cuts Don’t forget that I am using some of the parts from my existing chair, and that explains some of the oddities (e.g. the 9mm holes, the hole spacings on the seat plate, and so on).

The plans above should make sense – the 9mm holes are in the sides of the A and B struts, and there are a set of 5mm holes in the top faces of the B struts for the knee-cushion to be fixed to. All the holes go through both faces of the struts.

At the bottom end of the A and B struts, in the side faces, there needs to be a cut out 30mm across (the width of the box section metal) and with a radius of curvature of ¾” (so it fits the 1½” diameter tube which forms the feet of the chair).

I’ve spent a few hours over each night of the last week sanding the parts to remove corrosion and oil coating, cutting out the curved notches, and drilling holes. I’m hoping to at least start the assembly over the weekend.

EDIT: If you came to this page from a search engine, don’t forget to look for Kneeling Chair Project parts (#1), #2, #3, and #4 (plus a couple of updates) using the site search facility. This project is now complete and there are drawing/blueprints in the other parts.

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OK. This ongoing project for a DIY kneeling chair is well on its way now. Here’s the schematic of the parts I’m using and the relevant dimensions. You could call it ‘plans’ or ‘blueprint’, but I’m not making any claims in that area!

Also refer to the next article (Part #3) here.

EDIT: Please note the dimension in yellow… this corrects an error I discovered when I put the seating section together (it originally said 110mm).

Kneeling Chair - Updated Parts List I spent today (had most of the day off in order to get this going) trimming the parts. Last week I used an angle grinder to take the 3m lengths of 30mm box and 1½” round steel sections down to manageable pieces. The diagram below shows roughly how the parts will fit together – I’ll put up a better drawing with dimensions later.

Schematic Kneeling Chair (labelled)Basically, there are two seat struts (A) parallel to each other, and two knee struts (B) the same. The seat struts are closer together and fit inside the knee struts in a distorted X shape. I’ll use the spacers to make sure that the struts are the right distance apart.

You can see how those seat support struts (Aa) I mentioned in Part #1 will work. The original chair didn’t have these, so you can imagine how weak it would have been. In order to accommodate these struts I increased the size of the seat plate from the original, though the hole spacings will be the same. At a later stage I’m going to build my own upholstered seat and knee pads, but for the time being I’ll just transfer the ones off this existing chair (hence the hole spacings).

Anyway, I ended up using a good old hacksaw to cut the 45º angles. It was far less hassle then I’d imagined (from metalwork days back in school). I must confess I used the angle grinder and a coarse grinding wheel to trim the ends, though. I finished/squared these off with a metal file.

EDIT: If you came to this page from a search engine, don’t forget to look for Kneeling Chair Project parts (#1), #2, #3, and #4 (plus a couple of updates) using the site search facility. This project is now complete and there are drawings/blueprints in the other parts.

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Well, following on from my previous post on this project, the metal has arrived!

You can find Part #2 of this project here.

I’m just drawing up the plan I need for the component parts at the moment. I also nipped into Makro today and bought a few tools to make the job easier.

Fairline Bench GrinderMakro stocks a wide range of tools, especially the Fairline range. In the original post Welding Isn’t Easy I mentioned that I’d bought a Fairline arc welder – well, today I also bought a bench grinder . Hard to believe that it only cost £14.99! EDIT: Note that in the finished project I never actually used the grinder.

Looking at the poorly-built original chair I’m using as a template, one of the key weaknesses is the way the seat is attached to the main struts (and that’s apart from the fact that they didn’t weld it on all sides). The two struts are welded on to the plate at an angle of about 40° and although the angle itself isn’t crtitical, the fact that having only two contact points means that repeated standing up and sitting down flexes the Rough Design For Kneeling Chairmetal slightly. This eventually leads to fractures along lines of weakness – either the weld or across the strut itself. It’s all about cutting costs to save money as far as the manufacturers are concerned.

What I’m going to do is include a pair of smaller struts projecting almost vertically from the main struts on to the seat plate (these are not on the original – see diagram to the left). This will give four points of contact and create a strong triangular section (which adds strength). Combined with the fact I have chosen 2.5mm thick box section (the original looks to be about half this), it should yield a very strong finished article.

EDIT (20 May 2009): Incidentally, I was playing with various bits of software tonight and I’ve decided that there is no way I am going anywhere near drawing up a proper blueprint. I’d be here until Christmas! My sketches will be made using my existing art packages, which I know how to use properly.

Instead, I’m going to work out the dimensions of each component, produce them, then assemble them as sub-assemblies in stages. I’ve already measured up the existing chair and the most critical part is going to be making sure the spacing between the pairs of struts is correct to allow them to be inserted one inside the other.

EDIT: If you came to this page from a search engine, don’t forget to look for Kneeling Chair Project parts (#1), #2, #3, and #4 (plus a couple of updates) using the site search facility. This project is now complete and there are drawings/blueprints in the other parts.

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Right! A while back I wrote about how welding isn’t easy. Surprisingly, it has been one of the most popular pages – mainly people asking about sticking welding rods, or kneeling chairs.

There is an update to this project here.

I said that come the new year I was going to build a kneeling chair from scratch. One that is bomb-proof. Well, the project has begun, and I’ve ordered the materials from Metals4U (website at www-metals4u-co-uk with those dashes replaced by dots*):

Kneeling Chair3 metres of 1½” x 14swg mild steel tube for the floor spars

3 metres of 30mm x 30mm x 2.5mm mild steel box section for the main struts

500mm x 500mm x 3mm rolled mild steel plate for the seat mount and spacers

I’m going to draw up the plans (don’t expect a precise blueprint) and post them on here as an on going commentary of the project. I’ll also maybe take some pictures of the intermediate stages and – with any luck – I should end up with a solid metal kneeling chair along the same basic design lines as the one in that picture on the left, but minus the inherent design weaknesses I’ve discovered across three different purchases from online retailers.

To start with I’m going to use the riser and the seat/knee cushions off my existing one (which is falling apart again), but I want to make better/more comfortable cushions at some stage – and that will mean dabbling in woodworking and upholstery!

EDIT: If you came to this page from a search engine, don’t forget to look for Kneeling Chair Project parts (#1), #2, #3, and #4 (plus a couple of updates) using the site search facility. This project is now complete and there are drawing/blueprints in the other parts.

 

* Note that Metals4U asked me to remove the direct link to their site. As far as I can understand it, as well as getting too big for its boots these days, Google also appears to have outgrown its brain and is penalising companies for links to their websites from “lesser ranked” websites such as this one.

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Iroda Solderpro 120 Cordless Soldering IronAfter my irritation at having to queue in Maplin the other night, I went back today and bought that cordless soldering iron I was after.

The Iroda Solderpro 120 runs on butane gas. I’ve installed an extension cable in my car so I can run an inverter, and the terminals I used to connect it to the battery were just too bulky (a lot of metal in them) for my normal soldering irons to be able to cope with – they just couldn’t heat the metal up enough for the solder to form a pool and stick. For the record, I couldn’t even crimp the damned things properly, they’re that big.

This little tool is well up to the job. It charges up with butane very quickly and easily, and you don’t need any of those daft attachments to lose in the bottom of the tool box. It ignites immediately, and is ready to use in seconds. You can adjust the temperature with a small slider, so the tool actually rates at between 30-125W depending on the setting of this.

It is extremely well-built. It has a nice solid feel to it – reassuring when you’re effectively holding a bomb in your hand! You can also get attachments which turn it into a cutting tool for plastics, a tool for repairing jewellery, and so on. It operates as a pinpoint blow-torch if you take the tip off.

It made short work of fixing those badly crimped cables. They’re now well and truly soldered to the terminal rings.

Maplin also stock lower power versions – the Solderpro 50 and Solderpro 70. I’m seriously thinking of getting one of each of these as the convenience of not having a cable trailing and being able to solder in more comfortable situations is very appealing. I do quite a bit of soldering on computers and other electronic/electrical equipment and having to be close to a power outlet has always been a bit of a nuisance.

Iroda Solderpro 70 and Solderpro 50If you’re looking for a soldering iron and always thought – as I did – that cordless ones were pretty pathetic (some of them are), then this is really worth looking into.

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