Winter Warmth – a diesel heater for the workshop

Seems I need a New Plan for Winter

We got the electric bill for last winter and there was a sharp intake of breath … maybe the fan heater had been on too much in the workshop and maybe I did forgot to switch it off once or twice when going to bed …  something had to change.

I did some research on diesel heaters as used in motor homes and commercial vehicles and the concept looked like it would meet my needs.  I did some calculations on the workshop volume I needed to heat as an empty shell.  With my insulation and window content this came to a figure of 3kW.   Searching on EBay revealed lots of kits and ready built units so my first thought was to order a ready built one.  This duly arrived and I decided to run it up to see what happened.

Actually nothing really happened.   

The fan came on ran for a few seconds and then the unit shut down.   The controller was showing a severe droop on the supply volts even thought the PSU was rated at 10A.   More web reading and comparing notes with other users revealed these units take a serious current surge at switch on while the glow plug is warming up.   If it sees a voltage droop it thinks it is in a vehicle and switches off to protect the vehicle supply.

Bigger power supply acquired and plugged in.   Still no joy.   I then realised I needed to prime the fuel line.    Quite a few clicks of the pump later I had a full pipe feeding the device and finally it ran up.   The fan was flat out and the pump was clicking like a French grenouille on heat.

And what a stink it made.   I guess it was burning off all the manufacturing oils but it was pretty acrid.   Finally the fog cleared and I could see the neighbours house and we had heat.  Quite a lot of heat.   Fiddling with the pump rate brought the heat and the fan rate down and all seemed good.   But it was noisy.

There now followed some serious navel contemplation.  Did I really want this fire breathing Smaug inside the workshop ?   Not really.   So how to solve the installation ?

Immediate thought was to mount the unit external on the side wall and feed the warm air from the unit into the workshop and take in air from the outside to warm.   The smelly exhaust inlet and outlet would also then be outside.   Not a good idea taking outside air and warming it unless I wanted a very rust rich environment. 

So air would have to circulate from the workshop, get heated and blown back inside.  This means two 80mm holes in the workshop wall plus a power and controller wiring duct of say 20mm.   A plan was forming and I could see where the two air ducts could be located.

Next problem the (I have to say very horrible) enclosure my ready made heater came in would not protect the contents nor would it last very long sat in the outside air. 

original heater enclosure as bought
Empty original enclosure after stripping components

New Enclosure

Much Fusion 360 playing later I had a design based on a 20mm angle iron frame and aluminium sheet covering.

diesel heater enclosure fusion 360 model
Original Fusion 360 model of the enclosure frame less the two top bracing steels

The angle iron and sheet were ordered from Aluminium Warehouse and came very quickly.   I was now going to have to grasp the nettle and refresh my TIG welding knowledge to create my first major TIG construction.   (I only have TIG as MIG scares the **** out of me).

Even though I say it myself I was pretty chuffed with the frame that resulted.  Some of the welds were far from ticketable but my angle grinder and Hammerite paint soon covered up my ineptitude.

diesel heater angle iron frame
TIG welded heater angle iron frame after clean up and painting

The aluminium covers also stretched my resources as I don’t have a formal metal bender but I do have some very long lengths of angle iron and a robust vice.   Two side walls, a front panel and drop on top cover resulted without any serious clangs.  Loving it.

The return air inlet needed an interface of some sort so a Fusion model was created and printed (6 hour print …).

3D printed diesel heater 80mm air inlet cowl
3D printed diesel heater 80mm air inlet cowl which took 6 hours to print

With the enclosure complete, I mounted all the components and ran it up again.   The new power supply also failed to do the biz so I decided to go with a meatier version inside the workshop rather than inside the external cabinet.

Installation day loomed.   I was very ably assisted by Dave who is a long time friend.   We are both cut from the same engineering mould and we usually end up with an interactive plan of action.

First job was to cut the hot air duct hole in the workshop wall.   We had a long pilot drill, an EBay 80mm cutter and a SDS drill.   Serious grief.   The workshop outside brickwork  seemed to have a Titanium content.   We finally broke through into the cavity and thereafter the inner Thermalite block was like cutting chocolate cake in comparison.   First hole finished and more to the point in the correct position.

We now offered the unit to the wall to match the routing of the hot air outlet pipe of the heater.   We put a car jack under the unit to keep it in position while we drilled the mounting holes.  Holes drilled, we then mounted it on the wall and drilled the cable duct and lined it with a piece of uPVC water pipe.

diesel heater enclosure mounted on the workshop outside wall
Re-boxed diesel heater enclosure mounted on the workshop outside wall.  The pumps is enclosed in some foam to deaden the clicks.

The circulating return air from the workshop was to come through the workshop wall and back to the heater from just over a meter away.    I had a suitable length of 80mm spiral metal ducting for the air return and a mating right angle joint to route this through the wall.   We marked off the duct hole position and drilled out a second 80mm hole (more grief, less dust as we damped it down, and hammer and chisel when we got fed up with the useless 80mm cutter).

The Cunning Plan

I didn’t want the metal spiral ducting exposed to the elements and also saw it as a source of heat loss.   There is no point in heating up the workshop and then send the warmer air outside to lose heat on its way back to the heater.   The solution was to buy a standard 1m length of 110mm soil pipe and a right angle joint with two mounting clips from Wickes.   We wrapped the 80mm spiral duct in bubble wrap (quite a few turns) to fill the space inside the 110mm soil pipe to make a coaxial structure.    As luck would have it the spacing to the wall of the soil pipe was pretty much ideal to use the standard pipe clips.   We did however have to cut down the right angle soil pipe connector to get it flush to the wall.  It then got a dose of squirty foam to seal it.

Finished diesel heater enclosure with coaxial inlet duct
Finished diesel heater enclosure with coaxial inlet duct using 110mm soil pipework and fittings. The 80mm internal duct is wrapped in bubble wrap.

We were both very pleased with the result.   As Dave commented it looked better than a professional install would have done.

This was the bulk of outside work done apart from mounting the exhaust inlet and outlet pipes.   Inside we had the hot in wall vent grill to fix and the controller wiring.

I still haven’t decided where to route the outward air duct but currently it sits sucking air from under the Myford Super 7 cabinet.   I am not comfortable with this (the location rather than the potential draft around my ankles) as it will tend to suck up workshop dust and particles.   Some form of filter will be needed.   As yet I haven’t mounted the new power supply on the inside wall.

We ran it up and I can describe it as toasty warm.   At least one good reason to look forward to winter, probably the only one. 

Finally thanks to Dave for helping.  Also thanks to Steve Niebel for detailing his experiences with a similar unit.

If you want to know more about the heaters then the best source I found on YouTube was Dave McK 47

Anyone wanting a very basic indoor housing for their heater components should send me a message ….. and soon …. otherwise it is going in a skip (but I might save the handles).

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Lathe Four Jaw Chuck Laser Light Centring Aid

What on earth is this weird creation ? ……..

4 jaw chuck laser centring device

One of my favourite additions to the workshop has been a laser centring tool for use on my Tormach PCNC milling machine.   The tool consists of a low cost laser diode mounted on a 3D printed disc and with a 19mm steel shaft.   The tool is held in the Tormach spindle power drawbar.   The laser is angled inwards towards the spindle axis at approximately 20 degrees.   The 3D print has facilities for a battery supply and ON/OFF switch such that when the laser disc is pulled into the power tool bar collet it switches on the diode.

In use, as the spindle is raised or lowered, the rotating diode creates a circle of light on the milling table which can be used to locate and centre the spindle on features of the item being machined.   This might be to locate the centre of a hole or the centre of a block depending on need.

A full write up of the mill related item is available here.

I recently had the need to use my four jaw centring chuck on my Myford lathe.   Usually I duck and dive to avoid having to use the 4 jaw as I find it frustrating to set up.  This recent bout of frustration lead me to wonder if I could adapt my laser centring tool for use on the lathe such that it would give me a guide ring of light to show where the material was sitting relative to chuck centre.

On the milling version the laser rotates and the job stays fixed.   On a lathe version this would be similar.  The chuck would be stationary and the laser would rotate in the tailstock.

The full write up can be downloaded here. and the Fusion 360 file is here lathe_centring_device v4

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Machining a job that is outside a milling machine’s table travel using Fusion 360

Introduction

This write up is not for the purists with years of experience but is an explanation of how I thought through how to machine something over size that would not fit into my Tormach PCNC440 milling footprint as a single operation.  Hopefully it might help others to grasp the process.

The challenge began when a local turret clock expert came to me and asked if I could machine a new Hour and Minute Hand for a clock he was working on.   The Hour Hand was around 14” long and the Minute Hand some 18” long.   

Here is the Fusion 360 view of the minute Hand.

clock minute hand milled in three steps

Clearly these lengths were way outside the 440 table X movement (10”) so a plan was needed.  There then followed a lot of staring into the distance at mealtimes and also at bedtime accompanied by vocal “hmmm”s as I tried to mentally visualise what was needed.  This idiosyncrasy is something my wife has come to terms with over the years…..

My conclusion from this mental preparation was that I needed to be able to accurately step the stock across the tooling table and then take two or three bites at the profile machining.  

What follows would almost certainly benefit from a video but sadly I am not set up for this. 

Click the link below to download the PDF document.

Milling an oversize object

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Clock Wheel Cutting Adaptation of a Tormach Saw Mandrel

I am slowly building up to being able to cut wheels on the Tormach PCNC440 with two possible methods.

The first is using Gearwheel Designer which is mentioned elsewhere on my blog.   

The second route is  more conventional using a PP Thornton or similar cycloidal tooth cutter and a dividing device on a rotary table.  This later method is how wheels are traditionally cut in a lathe and there is a lot of information available on this.

In order to use the cycloidal cutters I need some form of arbor to mount the cutter in the Tormach spindle.   I could simply turn a piece of steel bar to suit and mount this in a ER collet in the spindle.   The downside of this simple approach is that every time the arbor was fitted into a collet the cutter would be at a different height from the table.   I really wanted something a bit more repeatable as the centre line of the rotary table will always be the same so why not the cutter centering.

When I ordered the Tormach PCNC440 I also ordered the Tormach small rotary saw arbor (which to date I have never used).   Pondering this last night I sketched up an adapter in Fusion 360 to allow an involute cutter to be fastened to the end of the saw arbor.   

This is shown below. It is made from a piece of 19mm AF hexagonal steel bar with the hexagonal flats going to be used as a tightening it in place in the Tormach arbor. My Myford Super 7 when used with a 3 jaw self centering chuck is not bad on concentricity but for really accurate centering I swap the chuck for a collet face plate instead.    This job was going to need both.

First operation was to turn the hex bar end that would screw into the arbor.  This was done in the lathe chuck.   It was a simple turn to a diameter and drill and tap the end with M6 to match the arbor mounting.   The only pain was the arbor has a slightly protruding lip so I had to undercut the mounting face for this.   Rather than trying to be clever I did it by hand using a graver.

While the hex stock was still in the lathe I roughly turned down the other end of the adapter to the primary diameter and slightly oversize for the cycloidal cutter bore diameter and then cut off the stock so far.

It would be important to get the cutter mounting running as square as possible so I swapped the lathe chuck for the collet plate and mounted the arbor end of the adapter in the collet. I carefully turned the shoulder for the cycloidal cutter diameter and then reduced the remaining length ready to cut a M6 thread.

Here are a couple of images of the finished adapter.

Tormach TTS saw collet with my adapter and a typical clock wheel cutter
Assembled cutter on Tormach TTS collet

I am pleased to say the idea went almost to plan and it runs very true in the Tormach spindle.

I was a bit over enthusiastic with the graver but this is of no consequence.

With hindsight the shank between the cutter and the hex section ought to be longer as this will restrict the diameter of the wheel that can be cut before the blank catches the hex section peaks.

One step closer to trying this method. The next experiment is to work on a sub routine in GCode to move the cutter back and forth while cutting and with the ability to easily program the number of cuts.

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A Lazy Cable Clamp using 3D Printing

This is nothing magic but worth a mention.   Being fundamentally lazy I don’t like to assemble and solder electronic multi-way connectors.   There is never enough room to work on the contacts and the cables never lay up how you would like them to.  This could have course be a function of my eyesight ..

I am currently working on boxing and installing the Tormach USB Expansion Board which has a USB connector interface.   I wanted the cable to pass through some form of gland into the box but didn’t want to cut a standard USB cable and remake the connector at one end of the other.   

After some head scratching I came up with the following simple cable gland/cable grip.  It is nothing revolutionary but made life easy and the parts only took 20 minutes to design in Fusion 360 and then 3D print on the Sindoh 3DWOX.

It has two identical semicircular halves that hold the cable and there is a ring that pushes over these on the outside of the box.   A small flange holds these in place on the inside of the box. The hole in the box and the ring inside diameter are both 16mm to allow the USB connector largest dimension to pass through.   This is also one of the standard cut rings on a cone cut hole drill which makes cutting the hole in the box very straightforward.

The component parts (two halves and the retaining ring)
Inside view of the gland showing the retaining shoulder on the two halves
Outside view of the cable gland showing the retaining ring

Not rocket science but you never know it might come in useful and the dimensions can be tweaked to suit other cables and connectors. Similar or related subjects : –