Morrisman
Forum Supporter
- Messages
- 9,030
- Location
- Staffordshire, England
I made the engine plates for my v8 bike from 1/2” ally. It never turned a wheel in anger but the plates looked cool.
- Thread starter Smallfry
- Start date
That's simply in torsion though - something that's hanging the box off the back of the engine has to resist the bending loads imposed by both the engine and box banging around over bumps etc as well. And worse if either contacts the ground - I have two Ford blocks where the box mounting lugs have been broken off when something hit the ground. There's quite a lot of momentum that builds up.
When the engine mounting holes and the bell-housing bolts are on very similar PCDs, then the plate can be reasonably thin, but the further apart they are in PCD, the thicker it will need to be.
I have seen instances where suitably cut about bits of bell-housing have been welded together to create a bespoke version.
Smallfry
HE's Spartacus.
- Messages
- 2,437
- Location
- Kent UK
Yes, I have noticed this. I was looking at the clutch plate for this engine, and the centre is only about 1mm thick, and its held with eight diddly little rivets !
I guess though, that all these things are in shear, rather than bend, so would make a big difference.
Morrisman
Forum Supporter
- Messages
- 9,030
- Location
- Staffordshire, England
And when you look at the torque output for many smaller engines you could put more load on it yourself with a 2’ breaker bar.
Smallfry
HE's Spartacus.
- Messages
- 2,437
- Location
- Kent UK
Have considered this, and there are none at all !
Agroshield
Member
- Messages
- 6,177
Getting the dxf from a template is not too difficult. With holes/dowels, you triangulate the measurements and write them down. You can establish a vertical line through the centre of the crank with a laser or spirit level and clock everything to that. So long as do everything at the same time, no part of the engine or box needs to be level or lined up. You can rotate and centralise the two pieces in the computer. A 'make the noise' digital level laid on two equal diameter dowels gives you an angle relative to the vertical. Outside-to-outside of two equal dowels minus one diameter gives the centre distance. With the main outline, you can lay it onto a piece of graph paper and draw around it. Having some way to measure radii is also useful but that can be a simple as finding a saucepan that fits the curve and measuring its diameter. You can lay the pan onto the curve and mark its centre on the graph paper.
If you put the best hand drawn drawing you can manage here, it is simple for someone to turn it into a dxf. The beauty is that you print that dxf full size on paper and confirm it is correct, tweak and repeat if it is not, then send to a laser cutter to be made in 1mm sheet metal*. If the sheet metal version works, you can go ahead with the thick version.
What I am trying to say is that you personally do not need any computer skills to do this, just the ability to make a well-dimensioned hand-drawn engineering drawing. The drawing itself does not need to be particularly to scale or neat as long as the dimensions are good.
* or even laser cut in thick cardboard
Things I consider when doing such measurements is the design person would hopefully have used sensible dimensions somewhere - what seems crazy figures up and down might be a sensible whole number radius at accessible angle.
Admittedly some of my colleagues seem determined to go against that idea though - fell across one to 3 decimal places on a fabrication this week
Admittedly some of my colleagues seem determined to go against that idea though - fell across one to 3 decimal places on a fabrication this week
I had a well respected engine tuner argue on a club forum that my technique for doing crank bolts up in gear, brakes on would excessively stress the flywheel, clutch etc. instead of some other complicated method he was suggesting.
I pointed out the required tightening torque was considerably less than the torque he was claiming from his engines . . . Silence . . .
DAPPH
as dyslexik as I'm daft
- Messages
- 7,489
- Location
- Near to Cross Hands Llanelli SouthWales GB
Furniture maker you say .. You should already have the necessary skills to make the pattern .it's just thinking out of the box a little on your part that's needed.Yes, getting it laser cut would be ideal, and save many hours of work with a junior hacksaw and my blunt files selection
I understand that cannot do it by using a paper/cardboard/ wooden template, and need a DWG or DXF file. I have no clue at all how to do this, and have a learning block when it comes to this sort of thing anyway.
I will do as Bob suggests, and continue to look on the internet for them, but unsurprisingly it seems those that have them, do not want to divulge.
Use a 0,5 mm mechanical pencil to sraw the plate using the engine case & the bell housing on opposite faces of the material e. Cut the engine side out first , cut the spline shaft hole with pins ,slip the gear box on and note the alignment of the mounts , make the template as below .
Perhaps make an accurate dummy plate in HDF or hard board then send it to get transferred to metal and water cut / Even if it is not the right thickness you just tell the the pattern cutting shop people what thickness you need.
On your pattern use clear fine extended construction lines and simple centre of hole marks on both sides of the board to get great accuracy . Then using a special spear pointed wood drill carefully drill out the holes to the correct size write the distances & hole sizes on the construction lines for reference s to be used by the people who draw up & cut the plate
If you need super acurate distances make a bridge to go ove the box & engine then slide pins to the right position ..
Having a £25 400mm or so digital scale on a backing strip here would be of great help and save you a lot of angst
Make your own centre of hole finders on your lathe either as pointed pins or to a known lesser diameter than the pin ,the shoulder to be just above the pin point whilst still keeping the hole diameter on the rest of the pin.
Once you get a reading add the diameter of one pin to find the centre to centre measurement to a few thou. When you have the plate made carefully draw the inside shape ,allowing for starter mounts and any clutch operating gear.
Kram
Member
- Messages
- 8,080
- Location
- Sussex
An ternative to gettingnit machined, is to carve it out with a large alu cut carbide burr. I have been suprised just how fast they turn alu to chips, tho on that size it would still be a long process.
Ally is easily melted, although the casting process does have some time consuming steps, the worst being to make up a large batch of casting sand/10% clay. Mixing is best done wet, but then can take a long time to dry before use. Not pleasant to make up in winter!
The most basic way to heat is a wood fire with an air blower, 10mm thick welded steel cruicible. Large proper cruicibles are relatively expensive unfortunately. I have some small ones.
From your 425/340 dimensions on previous page, 25mm thick is 3.5kg and 35mm thick is 4.8kg, so very doable on a diy scale.
You always loose a bit, so the melt would need to be 5-7kg - which you would easily get from a scrap wheel or cylinder head.
Ofcourse if you can find a suitable lump of fresh ali that could save a lot of effort
Ally is easily melted, although the casting process does have some time consuming steps, the worst being to make up a large batch of casting sand/10% clay. Mixing is best done wet, but then can take a long time to dry before use. Not pleasant to make up in winter!
The most basic way to heat is a wood fire with an air blower, 10mm thick welded steel cruicible. Large proper cruicibles are relatively expensive unfortunately. I have some small ones.
From your 425/340 dimensions on previous page, 25mm thick is 3.5kg and 35mm thick is 4.8kg, so very doable on a diy scale.
You always loose a bit, so the melt would need to be 5-7kg - which you would easily get from a scrap wheel or cylinder head.
Ofcourse if you can find a suitable lump of fresh ali that could save a lot of effort
- Messages
- 23,501
- Location
- Birmingham
Could be worse, I saw the layout drawings for the industrial unit I worked in, the floor measurements were to 6 decimal places!
DAPPH
as dyslexik as I'm daft
- Messages
- 7,489
- Location
- Near to Cross Hands Llanelli SouthWales GB
Thinking of the picture Ardy put up of his clean melted alu scrap . & the time I used a large 20 ounce washed out & dried peach tin as the melting pot in my log burner ..
I poured a complex support bracket into six day old dried in the airing cupboard plaster of Paris .
The broken bracket was super glued up and slipped onto a sheet of lightly stretched cling film then another added on top and the quickly tray filled . Then compacted with a carefully cut to size ply plate insert with me standing on it to get an accurate impression of the bracket , which eventually led me to make all manner of PoP casts for alu casting including a few thick plates .
To get a bigger plate perhaps pour quickly in an angle iron walled steel frame/ tray that has sloping sides & a 5 mm thick floor reinforced on the underside with angle iron...... so it will fall out when cold ?????
Morrisman
Forum Supporter
- Messages
- 9,030
- Location
- Staffordshire, England
The number of decimal places dictates what the tolerance is on that particular dimension. I can’t remember exactly how it works though, been 35 years since I worked in the machine shop.
