1908 Dennis Truck

[BenHawkins]

As mentioned on another thread we are preparing for future projects. There were a few hours spare this afternoon so we got the paint stripper out and started to clean the green paint off the valve caps and distributor drive. Under the green was red paint from its past life in a Liverpool salvage tender.

 

[BenHawkins]

It has been a good week for the purchasing department. There were a couple of good purchases from eBay including a job lot of Rotherham's of Coventry parts and we found quite a lot at Beaulieu autojumble. There is at least one item for each of the vehicles and quite a lot for stock. The Dennis car hub cap is just for the display case (not quite enough to start a project, yet).

[BenHawkins]

This project has been on hold for too long, we hope to restart it later this year.

The current project is a 1908 Singer (I could not come up with even a tenuous link to military for that one). I had one of the wheels rebuilt by an excellent wheelwright; he brought me a present for this Dennis along with the Singer wheel.

Back in 1976 he rescued a dilapidated horse van that appears to have been identical to those used by Carter Paterson and as originally repurposed to the body for this 1908 Dennis project.

The four parts are (top to bottom):

1. Shore Staff

2. Timber Standard

3. Tilt Hoop Iron

4. Outrave Stay 

I offered them up to the chassis and they look to be of the correct proportions so will be perfect to scale the body from.

He does not remember using any of the other parts to repair any other waggon so they are probably in the spares stock somewhere. I am now really looking forward to another visit to the wheelwright during the summer to hopefully collect a boot full of other rusty treasure.

[BenHawkins]

I have blasted the ironwork and really liked how the blacksmith tidied up the corner by forge welding a triangular piece in. 

 

They have cleaned up well. Repairing the threads that have been cut off will have to wait for a later date. 

I briefly looked at how much it would cost to reproduce the body in oak as used originally. Some shopping around will certainly be required.

[BenHawkins]

We have been tidying the garage so we can get back into this project soon.

I have been working through the information I have found on the gearbox and started to model it in CAD. There are 39 parts listed in the catalogue but there are no diagrams and it does not list things like bolts, keys and taper pins.

Drawings have survived for 14 of the components; this includes the four shafts but does not include the selector rods or gears. Much of this detail can be guessed at from the drawings in the patent.

One of the novel features is the freewheel mechanism. What force do you think the springs need to apply to the pawls to make it work reliably?

[rog8811]

Interesting design, unlike a sprag clutch  only two pawls will engage at any time, the springs will not need to be at all heavy as the shape of the pawls will self lock when in the detents.

Are you heading toward having all the parts for the gearbox made or hoping to find the right one or something of the era that will work?

[BenHawkins]

10 hours ago, rog8811 said:

Interesting design, unlike a sprag clutch  only two pawls will engage at any time, the springs will not need to be at all heavy as the shape of the pawls will self lock when in the detents.

Are you heading toward having all the parts for the gearbox made or hoping to find the right one or something of the era that will work?

I have a couple of 1920s Dennis gearboxes I could fit but I would prefer to put the correct version in. It is probably too much to hope that the correct gearbox will turn up so my only option will be to manufacture one. I don't like the idea of paying someone to have all the fun even if I was able afford it.

I have made a few of the simple components already but it is certainly going to be a challenging project.

[nz2]

Do any of the gears or shafts from the latter gear boxes measure up to be the same size as needed?

 

[andypugh]

On 5/17/2020 at 9:16 PM, BenHawkins said:

What force do you think the springs need to apply to the pawls to make it work reliably?

As-drawn the torque times the tangent of the angle of the face from a line from the centre point. (times  µ)  

If you sweep the extension of the pawl face to the other side of the centre point, just a bit more than the weight of the pawl. 

I keep meaning to design and build a CNC slotting head for my mill. Perhaps this is the excuse? 

[BenHawkins]

On 5/21/2020 at 12:43 AM, andypugh said:

As-drawn the torque times the tangent of the angle of the face from a line from the centre point. (times  µ)  

If you sweep the extension of the pawl face to the other side of the centre point, just a bit more than the weight of the pawl. 

I keep meaning to design and build a CNC slotting head for my mill. Perhaps this is the excuse? 

The ratchet detail is one of the drawings that survives. The tip angle of the pawl is 77 degrees and therefore I expected them to lock in when the hub is being driven. 

[BenHawkins]

On 5/18/2020 at 9:15 PM, nz2 said:

Do any of the gears or shafts from the latter gear boxes measure up to be the same size as needed?

 

The later gearboxes are stub tooth 5dp 20 degree pressure angle. The original was 6dp 14.5 degree pressure angle; shafts, covers etc. are all different but I may be able to use some of the transmission brake parts.

[andypugh]

On 5/21/2020 at 12:43 AM, andypugh said:

I keep meaning to design and build a CNC slotting head for my mill. Perhaps this is the excuse? 

Of course, you have a shaper with a slotting tool for it, so just need a dividing table that can be mounted at right angles to the shaper table. 

[BenHawkins]

There is still some detailing to do on the gearbox before I can consider making any more parts. I have decided that the priority tasks should be getting the steering and handbrake linked up to make it easier and safer to roll the chassis in and out of the garage.

The top of the steering box needs to be fixed to the dash. Although I started fitting the dash over a decade ago I left it 2" tall and didn't finish the dash irons as most other commercial vehicle engines would sit higher in the chassis. Now the project has the correct engine (thanks to Hedd and Ken!) I was able to finish the dash irons to the correct height by warming them up and bending them to match the original drawing (it is great how many of these have survived).

I then trimmed the bulkhead and cut the opening for the flywheel. Once the 14 holes were marked up and drilled I sorted out 5/16 BSW coach bolts and modified them in the usual Dennis way (filed three corners off the coach bolts and filed one corner into each hole in the dash.

 

The radiator pattern making stalled around 6 years ago for the same uncertainty about engine fitment. I have no drawings for these parts, just an idea of the overall dimensions and some cross sectional drawings of the Hallford horizontal tube radiator that also appears to have been supplied by Coventry Motor Fittings. I also have plenty of photos and these have also been very helpful.

On my 1914 Dennis the radiator flanges match the flange size on the White and Poppe engine so I have used the same for this design and also match the tie rod mounting detail. I have purchased one of the cheapest 3D printers to help work through the long list of patterns for this and other projects; it only has a 220mm x 220mm bed but can still do a lot of the detail work.

 

It is a horizontal tube radiator mounted on shackles. These features seem to have been in fashion for a year or so either side of 1908 before the vertical tube radiators mounted on trunnions became standard.

[David Herbert]

I like the left hand fitting on the radiator top tank. Those 3D printed details are very nice.

David

[BenHawkins]

On 5/25/2020 at 9:34 PM, David Herbert said:

I like the left hand fitting on the radiator top tank. Those 3D printed details are very nice.

David

The pig was a test print. I think the castings, tube plates and tube will cost more coins than it can hold.

[BenHawkins]

I have made a few BS190 bolts and slotted nuts to secure the steering box this week, once painted I will fit them.

So far I do not have the confidence to leave the 3D printer going when I am out of the house but some more of the radiator pattern parts are finished.

I need to get the router out to shape the bits of MDF but we hired a skip this week so I have been moving large rocks and soil and every opportunity.

Three of the water connections between the cylinder blocks are corroded away or broken. I made a CAD model of the pattern and core box. The pattern took around 13 hours to print, the core box will take about double that.

 

 

[andypugh]

53 minutes ago, BenHawkins said:

The pattern took around 13 hours to print, the core box will take about double that.

I wonder if there is a way to print just a thin shell then fill with expanding foam? 

Or maybe use a very sparse porous fill pattern and pour in 2-part resin. 

Don't forget to leave a hole to glue a dowel in so that the moulder can insert a screw to pull the pattern out of the sand.  (CAD makes it trivial to put that at the exact centre of gravity)

Edited May 31, 2020 by andypugh

[Citroman]

You can print a thin shell with a web like support structure printed under/with it.  The pig makes a nice radiator mascot...

[BenHawkins]

On 5/31/2020 at 7:32 PM, andypugh said:

Don't forget to leave a hole to glue a dowel in so that the moulder can insert a screw to pull the pattern out of the sand.  (CAD makes it trivial to put that at the exact centre of gravity)

I picked up a free sample bag of threaded inserts at a engineering trade show and have been using those in the back of smaller patterns. I decided to print little handles to fit to M4 set screws as well.

 

The project is not so much of a rush that I need to get something printed every day so I am printing small items in the evening and get a couple of the larger parts at the weekend. I am using a relatively small layer height (0.15mm) and thick walls so could print faster with thicker layers.

 

[BenHawkins]

When I was having MDF shapes CNC machined for patterns some time ago (for the 1914 Dennis) we managed to fit in a couple of profiles for the header tank into the sheet (but not a complete set for the pattern). I have quite a bit of MDF left over from the mock cab I built (also for the 1914 Dennis) so I have cuts some pieces out a little larger than the templates. After making a couple of aluminium top hat pillars to pass through them (tapped M6 to help extract the pattern from the sand) I glued a couple of them together on the table in my office (as that is reasonably flat and will not upset the glamorous assistant as much as doing it on the kitchen table).

 

I then took them out into the yard and used some plastic strips (printed to the correct thickness) to offset the router cutter and make the second layer slightly larger than the first and give the pattern a sensible draft angle so it should pull from the sand. I need to repeat this several times before I can screw and glue the printed parts to them.

[BenHawkins]

Yesterday we printed the first half of the core box for the water connectors whilst I was working on other projects.

 

The pattern had a couple of coats of bondaprimer and some rubbing back during the week and is starting to look good. The first half of the core box has had a light sanding and a coat of primer; the second half is hot off the printer.

 

[Rootes75]

40 minutes ago, BenHawkins said:

Yesterday we printed the first half of the core box for the water connectors whilst I was working on other projects.

 

The pattern had a couple of coats of bondaprimer and some rubbing back during the week and is starting to look good. The first half of the core box has had a light sanding and a coat of primer; the second half is hot off the printer.

 

Looks like very good work to me, we have a 3D printer at work and they are very handy for homework!

[BenHawkins]

We are still mainly concentrating on other (long neglected building) projects but really enjoying getting back into this one after so long.

I have glued each additional layer of MDF onto the CNC cut templates and used the router to trim them with a slight offset to give 2 degrees of draft angle. Each is currently at 4 layers of 12mm and the final depth needs to be 4" so I need to add some thin ply or similar to the backs to finish them off. There are still a few more parts to print before moving on to the core box. 

 

The outlet is on the side of the radiator so a tight bend is needed. Three of the four parts of the pattern have been printed, rubbed down and primed; the other half of the core box is currently printing.

 

[BenHawkins]

These patterns have been given a couple of coats of paint and will need polishing when the patterncoat has hardened.

 

I have added 3mm of ply to each stack of MDF for the header tank pattern to make up the thickness. I then drilled holes for dowels to line the two halves up. 

[BenHawkins]

Yesterday morning we had a drive down to Somerset; setting off early to avoid the queue of caravans heading south now they are allowed to stay over night.

We spent five hours picking through piles of cart and carriage ironwork in an attempt to find all the remaining parts from the long dismantled Lyons tea van. It was moderately successful as we came back with a boot full of iron for this and some other projects.

 

Am I a rustaholic, or do I just think I am? Anyway, it is not a complete set so I will continue to build my blacksmiths shop.

During the week I drilled the two halves of the header tank pattern so I could fit the alignment dowels. This morning I marked the location for the filler and drilled a 20mm hole to locate the 3D printed filler neck and core print.

 

After the filler neck halves were glued and screwed in place a bit of filler was used to blend them in and cover the screw heads before I gave them a coat of bondaprimer.