Author Topic: Len Mason's "Mastiff" - chewed from the solid  (Read 33426 times)

Offline ozzie46

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #15 on: September 17, 2016, 02:36:04 PM »
Maybe because it was originally designed to power a boat?  Just a guess,but in the series in ME he said it would power a 6 foot boat.


 Ron

Offline ozzie46

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #16 on: September 17, 2016, 02:49:52 PM »
Here's a link to the one I finished in 2013. I need to make new rods  as 1 is no good now.  I made them out of 6061 ally. The new ones will be 2024 ally. Also i am going to move the distributor to the top of the points casing as is usual. Oil is getting in the one as designed and shorting things out. It has hall effect ignition.
 The blk/crankcase is built up of thick plate that is screwed and JB welded together. Works great and saved money on a large solid block that would have had to be milled out. 

 The engine is all carved from "solid" except for the screwed and glued crank case. Also made my own scew gears.

 It was my first IC engine and there is room for improvement in running and making a good looking stand.





Ron

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #17 on: September 17, 2016, 11:29:32 PM »
Thanks for sharing that Ron, great to see one working. I've read elsewhere that the carburetter can be tricky to make and get to work, did you buy in a commercial unit? I thought about a built-up crankcase, definitely less swarf with that approach, but the idea of carving from the solid appealed more.

First up I'll try to get the original ignition system to work but a Hall effect unit is a good option. As a family we've owned a few Subarus and the "waste spark" system they use looks worth try too.

DT

Offline ozzie46

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #18 on: September 18, 2016, 12:37:19 AM »
Thanks for sharing that Ron, great to see one working. I've read elsewhere that the carburetter can be tricky to make and get to work, did you buy in a commercial unit?

DT

I actually used a carb designed by a member here, George Britnell aka gbritnell. He has posted on this thread already. He has made the plans freely available in the past, maybe he will post them again.

 Ron

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #19 on: September 22, 2016, 09:45:28 AM »
Here is a description of making my version of the Mastiff crankcase. The aims of the redesign were to make the crankcase from a single piece of metal (accepting that this would involve making a lot of swarf) and to have sufficient thickness for all the cylinder block studs to be held in tapped holes. All threads have been changed to metric, mostly standard pitches but some fine threads.

Listening to advice from other members I'll include drawings only for bits that I have modified significantly. I haven't generated a full set of drawings from the CAD model, I'm just making them as I need them. Here are the crankcase, bearing housing and associated bits:



A pdf version is also attached as the jpegs from Geomagic Design (GD) are poor. I hope most people get to see the images, I'm using MS OneDrive for picture hosting and getting the pictures to appear wasn't easy. Many thanks to the members who helped sort this out in another thread; Firefox under Windows 10 works but IE 11 and MS Edge seem a bit less certain. If this causes too many problems I may have to re-post using attachments.

The starting point is a billet trued-up in a nest on the mill:



and swarf was made:


the surface cleaned up by fly-cutting to size:


which produced a nice, silky smooth finish:


that, despite all the care I took with clamping didn't survive intact. The billet was marked out and mounted for boring:


drilled through and a 12 mm boring bar used to bore right through. This proved too ambitious and the finish at the far end was entirely chatter marks (should have expected this). The recovery from this is shown later. In this picture you can see the home made depth-stop and slips used to control the depth of boring:


the 16 mm bar with a polished tip gave a really good finish. It also produced dense rats nests of swarf in the hole that had to be dug out frequently with a dental probe. The tooth brush was to keep the depth stop clean:


with the main bore finished to size and depth the angle plate was moved to drill and bore the camshaft tunnel:



to recover the hacked-up timing end bearing mounting I turned a mandrel from MS:



and mounted up the block:



the bearing mounting ended up over size but not so much that the bearing won't come out of the material supplied.

Then it was back to the Aciera to drill and bore out the holes for the cylinder liners. The plug gauge needed to keep sizes in order is shown as well:


Then the mill table was tilted to 13 degrees and the tappet guide bores drilled and reamed:



and the clearance milled in:


To finish off the part the holes in the top and bottom of the block were milled out:



The finished part  looks like:


and with the flywheel end bearing fitted:


At this stage a rod fitted in the crankshaft bearings turned smoothly with very little shake. The camshaft bearings however weren't well enough aligned and I turned down the outside of the bearing to allow it to move slightly. This may not have been a good idea as the oil feed goes through this and I'll have to work out a way of sealing the bearing in its mounting.

This is my first attempt at a bulid log so I'd appreciate any and all comments! Hope there isn't too much detail in this post?

DT

Online Jasonb

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #20 on: September 22, 2016, 10:59:51 AM »
Pictures are showing up fine and you are off to a good start. I also find it best to print the GD drawings to pdf as it seems the best way to publish them. Presentation of your build is fine and having the images in amoung the text is worth the extra effort involved.

Have you been following the twice size one that is being covered in ME at the moment?

J

Offline Admiral_dk

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #21 on: September 22, 2016, 06:38:42 PM »
I haven't been round to the other thread, but pictures are showing up nicely here and are looking good  :praise2:

Offline Dave Otto

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #22 on: September 22, 2016, 08:11:05 PM »
Hi DT

Everything is looking great; nice pictures and good information. I will be looking forward to more installments from your Mastiff build.

Dave

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #23 on: September 28, 2016, 03:07:12 PM »
OK, having made the crankcase and the flywheel end bearing I wanted a moving bit so I made the crankshaft. This is the first I.C. engine crank I've made and also the first with more than one throw so I was nervous. Another reason for making this was that it got what I perceived as a difficult bit out of the way.

As Len Mason points out in the book carving big, asymetrical, chunks out of BMS flat can lead to stresses relieving themselves all over the place and the finished part distorting; definitely something to be avoided. Many years ago I managed to "catch" a muffle furnace as it was being thrown out at work, apparently it no longer got hot enough to be useful. The crank blank was a chance to try this out for stress-relieving steel and the good book told me I'd need to hold the blank at ~900C for an hour or two. At first sight the thrower of the furnace was right, the best I could get on the meter was 400C in a furnace that should reach 1200. I wasn't totally convinced and reached for the multimeter and a thermocouple - actual temperature close to 900 and a (very quick and indirect) look inside showed an appropriate colour so I slid the bar in without any more thought. Of course I'd forgotten about scale and when the whole lot had cooled down the blank looked very rough and flakey (sorry, no picture of this) and had to be machined all over to recover:



A lot of this machining was needed anyway but I need to find an Australian source for anti-scaling compound. I've bought "Cherry Red" case hardening compound from a bloke in Qld but he doesn't look to sell the other stuff.

Apart from using Metric fine threads I haven't changed the design of the crank so I won't include a drawing here. The machining mostly followed the book but modified for the available kit which makes thing a lot easier then it would be with an ML7 and a vertical slide. The next step was to put in the three centres at each end:



using an angle plate nest on the X3 drill-mill, drilling one centre then turning the blank end-for-end to drill to corresponding one should leave these very well aligned.
After some drill and hacksaw work the middle centres were used to rough turn the journals with R and L-hand tangential tools and turn the outside of the webs:



No pictures of the Eccentric Engineering tangential tools in action but these are well worth the money. I was sceptical of these in the past but I bought the Aciera F3 from Des Burke who was the original designer of these and, being a real gentleman, Des gave me one of the tools with the mill. They work!

More drilling and sawing to rough out the crankpins and then a long series endmill cleaned up the flanks of the webs (less nerve-wracking for me than turning this skinny, wobbly, piece of metal between centres) :



Eventually I had to get on and, very carefully, turn the middle crankpins with conventional L and R-hand HSS tools that were stiff enough to reach in:



For the other two crankpins I ground a 1/8" parting blade with a "forked" end as recommended by LM:



and in close-up:



I'm pleased with the finish this gave and was very relieved to get this sequence over with. The keyway for the crankshaft timing gear needs a single point tool making. There's no point in trying to file this across a diameter when the real thing is available:



I think I left it too soft after tempering and the cutting edge didn't last too well. However, the keyway cleaned up close to the correct width:



The two threads were screw-cut with 0.75 pitch and finished with dies but I didn't take pictures. The VFD on the Hercus gives almost instant stop and easy reversing and this has taken much of the stress out of screw cutting as well as speeding things up a lot. The last operations were to drill the oil passages in the crank and the tension rose again, breaking off a drill in the work at this stage would not be good. New long series drills cut well and gave plenty of clearance and visibility and all went well:



The finished product:



The proof of this particular pudding was in the mounting in the crankcase and the crank turns smoothly with very small clearances. No post-machining distortion has occured so either the metal was good from the start or the stress-relieving worked.

Now I will start making more ali swarf and carve out the base and sump.

DT

Online Jo

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #24 on: September 28, 2016, 03:11:36 PM »
 8)

Jo
Usus est optimum magister

Offline crueby

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #25 on: September 28, 2016, 04:42:52 PM »
That crankshaft came out wonderfully!

I have not seen the forked end on the parting tool like that before, what is the reason for it? Is that mainly used for back/forth turning of the surface rather than straight-in parting action? If so, I guess it acts like both a left-handed and a right-handed turning tool?

Offline b.lindsey

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #26 on: September 28, 2016, 11:59:54 PM »
Great build log thus far DT and excellent pictures to go along with it. Keep it up just as you are doing :)

Bill

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #27 on: September 29, 2016, 12:43:45 AM »
Thanks everyone for the encouragement!

The forked parting tool was suggested by Len Mason with the claim that this gave the stiffness of a wide tool with the cutting edge (and therefore cutting forces) of a narrow one. Just what you need when the tool overhang is extreme. Also you get L- and R-hand tools in one so no messing about with changing tools. I was very pleased with the finish produced, small plunge cuts followed by careful L and R movements did the job.

DT

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #28 on: October 22, 2016, 04:32:28 AM »
I hope that members will be interested in the 3D CAD model of the "Mastiff from the solid" project so I've exported it from Geomagic Design as a 3D .pdf file.

I have failed a few times to post the file on the Forum, the "Internal Server Error" isn't very helpful or informative but I guess the .pdf file is too big for the system. As an alternative I've loaded it in to OneDrive and created a link for downloads:

https://1drv.ms/b/s!AnNmmwsT2XIigi23PfPITSHAp56_

This file works well when viewed using Adobe Reader DC but doesn't, in my experience, work when you open it in a browser. The file format allows you to view the whole model or any component part (or group of parts) and to cut a section through it at any angle you fancy. If anyone needs any more help with viewing, please ask - it took me a while to find all the features by experiment.

I think the best images appear when you set the "Model Render Mode" to solid outline and the "Enable Extra Lighting" setting to "White Lights" (this is the default anyway).

DT

Offline steamer

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #29 on: October 22, 2016, 12:28:40 PM »
Nicely done DT!    I'll be doing something very similar this weekend.

Dave
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