Further Diesel Heater Update

As mentioned on a previous post, I came across a YouTube video regarding a UK source of an electronic replacement for the mechanical pump for use with my 3kW diesel heater. I ordered one of these and have just installed it.

James Browning does not have a website. You send him an email to the address below and he sends you the details of his product. Note that you need to copy his address into your messaging app as the link below is an image not a URL. This affords him some protection against spam.

Installation of James’ box is straightforward with copious notes and videos to assist. Connections are simple – +12V, 0V and the two old wires originally going to the mechanical pump. You need to route the fuel feed via his box and then before running the heater you need to bleed the air from the pipework. There is a handy little switch in the box to help do this.

There is a knob on the box that alters the fuel mix which you can tweak with altitude. This is relevant if you are touring in a mobile home but not for my installation heating the workshop. The box as delivered has the fuel mix set to sea level operation and as I am at 90m asl I left it untouched.

So what have I noticed ?

First of all the old ticking noise has gone and the burner noise is more even. Major plus.

With the mechanical pump I had to put a metal plate against the wall to stop the soot staining the brickwork. Clearly the burn as it was was not correctly balanced to have caused this. With the new electronic pump all I have is condensation dribbling down the plate (it is freezing cold outside) so the burn is more efficient.

I can now burn our domestic heating oil (kero) as the fuel does not need to have any lubrication content as it did for the mechanical pump. Currently in the UK domestic heating oil is around GBP0.70 per litre and road diesel is GBP1.60 so a direct net saving amortising the cost of James’ unit.

Conclusion therefore : -no ticking, more efficient burn, lower cost fuel leading to an overall fast investment return and ultimately a net saving.

So far I am very pleased with the upgrade to my heater and I wish James every success with his innovation.

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Myford Super 7 Large Bore depth stop

I recently had to turn a number of items on my lathe and wanted them to be consistent in length. These were long items, too long to reference with my home made Morse Taper depth stop.

In desperation I raided my Sherline CNC Rotary Table hardware kit for my coaxial tailstock clamp. This is based on the Myford tailstock winding handle but without the handle. It clamps the lathe bore to the CNC table for cutting items needing indexing such as clock wheels. Wheel cutting is quite a demanding application. There is no tolerance for slippage or you will get to the last tooth and have only half half the material that you expected left to cut … and the box of shame looms.

The clamp is quite simple – the main body is an expanding collet, this mates with an expansion cone and a centre threaded rod. The cone angle is 5 degrees. There is a knob to tighten the assembly and squeeze the cone into the body to expand its arms. The body has four slots that two pins on the cone engage with to stop rotation.

Having finished the particular job in hand I put away the Sherline clamp and thought it would be useful to make a second version of the clamping collet dedicated as a lathe depth stop. I was rummaging in my metal stock for material to make this when the light bulb came on …. why not 3D print it? When the clamp is used as a depth stop there is no rotational stress. It just acts as a stationary reference stop that sits down the lathe bore.

I copied the dimensions from the Sherline version and input this into Fusion. I printed the body, the cone and a knob (with an M8 embedded nut). The centre rod is M8 studding which passes through the collet body and then screws into the cone and then protrudes onwards to set the depth in the lathe bore. You would think that there needs to be a nut to lock the studding to the cone but the cone cannot rotate as it has the two locating pins. Providing the studding is stopped from rotation while the knob is tightened, the depth should be set solidly. A lathe depth stock is rarely an accurate setting tool but just a repeatable reference. The accuracy of the final cut is catered for by the tool position set and the various lathe DROs.

Printing this was a lot easier than cutting it from metal. No messing setting cutting angles etc. Here is the Fusion pictorial view and cross section.

After using it a couple of times I ended up putting a spring and two M8 washers between the body and the knob to maintain a slight pressure on the cone. The spring keeps the locating pins engaged in the slots on the body as the assembly is pushed in place down the spindle bore.

I also added a ‘top hat’ on the end of the M8 rod (not shown above) to give a larger surface area for the work piece to bear against. This would also stop wobble of the threaded rod as the spindle rotates.

Attached below is a ZIP file with the body, cone, top hat and knob STL files. You will need some M8 studding, an M8 nut and some short M3 stubs for the anti rotation pins in the cone. If you add the spring then two M8 washers will be needed. All the threads are modelled in the STL files but will need cleaning up post printing. I printed in PLA+ and had the prints set to four perimeters. I superglued the two M3 studs in place. The tops of the studs should not protrude beyond the unexpanded body surface otherwise they will bind on the inside surface of the spindle bore.

Things now went a little bit off piste …. I had forgotten that the end of the lathe spindle has a threaded section that mounts the bearing pressure collar. The exposed thread is normally protected with a plain collar. The thread is M35 x 1.5, something very easy to model and print via Fusion 360. Below is the relevant exposed thread with the protector collar removed.

Another light bulb came on (getting to be competition to Blackpool you might think). Why not make things very much simpler?

I modelled a boss to screw onto the M35 thread with a central core to fit down the spindle bore (26mm) and with a central M8 tapped hole. I also printed another through hole M8 knob, a M8 top hat and a new blind M8 knob. I now had a much more simple depth stop.

Here is the Fusion image of the boss. This would have been very difficult to cut as one piece in metal but very simple as a 3D print.

Here is a close up view of the final assembly with the top hat out of shot at the far end of the M8 studding but shown in the second image. The knob on the left grips the end of the studding to allow easy adjustment of the position of the top hat. The inner knob locks the studding in place against the boss. Both knobs have embedded M8 nuts. (Note the bend on studding is a photographic distortion).

Two solutions for a depth stop. The second option is peculiar to the Myford and the first solution more universally adaptable to other lathes. The following download ZIP file contains the STL files for both versions and there is a second ZIP which has the Fusion 360 model for those wanting to tweak. Either version will make a useful addition to the workshop tooling.

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Tormach Power Drawbar piston service

For some time my compressor has been intermittently kicking in without anything running to justify it. By chance I heard a slight hiss and then felt a small ‘breeze’ coming from the bottom of the Tormach drawbar compression cylinder stack. This device has three pistons stacked together to give enough downward pressure to open the drawbar gripping the TTS collet. The machine was installed in 2016 so the seals have done quite well to survive this long.

I did some web based research and found that Tormach offer a seal replacement kit so clearly this was something that was an expected service activity. I ordered the kit (which cost less than the courier charge). Here is an image of the kit.

My research also found a very old YouTube post by John Saunders at NYC CNC where he describes how to undertake the service activity. It looked like a job I could manage.

My PCNC440 model was slightly different to John’s in so far as removing the piston assembly out of the machine. On mine you have to just remove a single shoulder bolt and a pull out pin. However before doing this you need to put any of your TTS tools in the collet to relieve the pressure from the cylinder plunger head. Once this is done, turn off and bleed the air supply before removing the two air feeds. Mark them so you know which one goes to which port. Also mark the three piston sections with a Sharpie so you know which order and orientation they are in.

The piston stack has the three sections clamped together with four bolts inserted from the top of the stack. The bottom end mounting plate also has long screws that pass through spacer tubes but only fasten into the bottom piston section. Note that these spacer tubes might well have some large additional height setting washers so don’t lose them.

I suggest removing the bottom three screws first of all so you are left with just the three cylinders still held together by the top four bolts.

Now for a tricky part – you need to remove the large circlips that are fitted to the top and bottom ends of the piston stack. These are not easy to remove unless you have a decent tool to grip them. Basic handheld circlip pliers are unlikely to perform and you could end up search the workshop for flying circlips. For this reason you must wear some eye protection while removing the circlips. I bought in a pair of these pliers and they were superb for the job.

Once the circlips are removed you can remove the four top bolts holding the stack together and be able to split the three sections. Be careful how you do this so you see and understand what is where and the order of assembly.

The end plates that were held by the circlips are pushed outwards. All the other sections should freely slide out as appropriate.

With everything ready, start from one end of the assembly and do a logical swap out of the old seal and swap in the new one and re-assemble that section. Clean off any debris in the seal grooves and add new grease to the seals and their locating grooves. I used silicon grease.

The kit comes with 6 standard section O rings, 3 wider section rings and 3 central piston seals as shown in the image above. By swapping only one seal in and out at any one time you get a good control check that you haven’t missed anything.

My kit also had some small O rings that are not shown in the Tormach image of the kit contents. I can only assume that the kit is universal to a number of other piston types.

Update : Tormach has since confirmed that the extra small O rings are for the 770 and 1100 versions only.

The whole swap out activity took around 2 hours. This piston worked fine when re-installed back on the 440. “Phew!”

Eccentric Engineering Turnado arrives

Another asset to the workshop tooling register

I love to use gravers. It is like turning wood but with metal.

I have four regular use gravers made to William Smith’s receipe, two for general turning, two for parting. These get used in conjunction with my Hemminway quick release hand turning rest as shown below.

There is something very therapeutic about being in direct contact with the material being worked on rather than being decoupled through a tool post and handwheels.

I have a potential project looming that will require hand turning and on a larger scale than is practical with my gravers. If I had a CNC lathe this would be straightforward but alas this is something maybe for the future. After some research I came across the Eccentric Engineering Turnado hand turning device. There are a few videos on YouTube about it and I believe Quinn at Blondie Hacks uses one. She also uses Eccentric Engineering’s tangential/diamond toolpost which is another of Gary’s useful products. Here is a screenshot from Gary’s site.

I took the plunge and ordered a Turnado. It arrived on my doorstep here in the UK 3 days after posting from Australia which was impressive.

The kit as received needs dedicating to the lathe on which it will be used. This involves deciding how to mount the working table on the carriage and setting the lathe centre height correctly. Setting the table height involves turning down five pillars to the correct length – quite a simple process you would think…. but I blew it and cut them too short. Totally inexcusable clang and I had to remake them. Very red face and very blue language resulted. The correct gap between the two plates was 12.7mm on my Myford.

The mounting on the Myford carriage needs a round boss that matches the boss under the standard top slide assembly. I measured this as best I could, modelled it in Fusion and 3D printed a prototype.

The 3D model worked fine. With confidence restored in my ability to measure properly I turned up the boss in steel. All went well and the Turnado table mounted correctly and gripped very well on the lathe carriage. Here is a picture of the lower side of my finished assembly. Apologises for the pink 3D model – of late I have had a heavy demand from grandchildren for Barbie related models.

Having now played with the Turnado I can say that it is a lovely well thought out piece of engineering and works well. Using the hand tool is a delight and the accessories for profile turning will be indispensable.

Nice product Gary.

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Workshop Diesel Heater Update

Some answers to questions from readers

My blog post about installing a Chinese RV diesel heater in my workshop is probably the most popular post visited on my blog. This has been even more so with the present cost of fuel and the onset of winter weather. You can read my original post here and I suggest you read that post first of all to make more sense of what follows.

First let me say that installing the heater was one of the best workshop improvements I ever made. The heater performs very well and quickly gets my working area up to temperature. My opinion needs a bit more defining.

My workshop is contained in what should be the house garage and is roughly 6m x 4m x 2.5m. It is built onto the side of the house and has one outside wall which is an unfilled standard brick cavity. I have covered the garage door with 1″ Cellotex equivalent foam boarding. This was convenient to mount to match the door construction and probably the thickest I could use without impacting on the garage door operation. My wife has provided a door bottom ‘sausage’ muffler filled with polystyrene beads. The door is therefore relatively draft proof but not perfect.

The roof over the workshop is double skin plasterboard and has timber joists with 6″ of fibre wool insulation.

With the current overnight temperatures (-4C) the temperature in the workshop drops to around 15C. The heater is a 5kW branded model but likely to be only 3kW in practice. It takes around 1 hour to get the temperature up to 19 to 20C in the present externally very cold conditions.

Fuel – I use an approximate mix of domestic heating oil (40%) and vehicle diesel (60%). Why do I do this apart from cost saving ? I have read that domestic heating oil does not have sufficient lubrication content to lubricate the demand pump action in the heater. I therefore err on the conservative side and use a mix of the two. I have no idea whether this is fact or fiction. I do not have access to red (Agri) diesel so this is not an option for me to use but clearly would be the cheapest route and would provide the necessary pump lubrication.

I have a 20 litre diesel storage can which I fill at the local garage every 2 or 3 weeks. This is eyeball mix tipped into the heater internal 5 litre tank together with the heating oil which I siphon out of our domestic tank as needed. I would estimate that I use 5 litres of the mix every 3 to 4 days depending on outside temperatures and based on at least an 8 hour day ‘making things to make things’ as my wife calls it. If the heater tank runs dry I find I do not have to re-prime the heater pump but simply refill the tank and switch back on.

The heater controller is the second one I have fitted. The display died on the first one. The controller is easy to use and allows timed operation, set temperatures and live temperature readouts. It is a three wire connection and I had to extend the cable length with a spliced in 3 core section. The OK button cycles round the various display readings and the ON/OFF symbolled button is the lower middle button. The heater needs a single very short press to start the heater up and a longer press to shut it down. Over pressing the ‘start’ leads to an abortive shut down procedure. The left and right arrows increment the various settings selected by the OK button.

The start up current is very high, around 10A at 12V. The choice of power supply is therefore important to be able to sustain this surge. The controller display allows the value of the supply voltage to be checked. The heater once started roars away at full pump speed (a very fast clacking noise) and once at the temperature set point the clicking drops down to a slow tick. There is an icon on the display that mimics the tick. The sound from the ticking is conducted into the workshop via the inlet and outlet air ducts. Like the ticking of a clock, you just get used to it and mentally cancel it out. Both the roaring at switch on and the ticking are louder outside the workshop than inside but these do abate once the heater reaches the set temperature. I am conscious that both the roar and the tick are probably audible with the neighbours but their ground source heat pump is equally audible to us.

The shut down procedure after the long press on the controller button initiates a full bore roar from the heater. I assume this is to burn off accumulated soot in the heater from the slow background tick reached at temperature set point.

As mentioned above the exhaust is noisy. I believe that the choice of silencer affects this. Straight through ones are to be avoided. There is also some discussion about having two in series to reduce the noise further. I have not tried this. Note also that the exhaust does create black soot so I have fitted an aluminium sheet on the wall to protect the brickwork. Standard shower cleaner spray with a bleach content does remove this. The soot plate can be seen in the image below along with the 20 litre top up container.

My prior post about how I installed the heater details the inlet and outlet duct locations. The heat outlet grill is on the workshop wall between my two milling machines. This is not ideal but was the only practical location. The return is under the Myford stand.

The heat outlet has the shortest duct run being almost directly at right angles through the wall from the heater burner outlet. The return duct is located under my Myford lathe stand and is a simply constructed wide mouth housing tapering down to the flexible duct that connects back to the well insulated ducting along the outside wall to the heater. I have fitted a fine gauze mesh over the mouth of the taper to stop debris entering the heater. The image below gives some idea of the construction to fit the available gap under the Myford.

I think I have covered most of the questions asked by readers but feel free to contact me if you need to know anything further. Clearly everyone’s setup is different but for my workshop this is an outstanding and relatively low cost comfort benefit. It also creates dry recirculating air that benefits my equipment.

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