Author Topic: Len Mason's "Mastiff" - chewed from the solid  (Read 23589 times)

Offline john mills

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #150 on: June 27, 2018, 07:33:28 AM »
Art
I did't do much good at maths i think i got about 30 for math b in 5th form then latter spent 20 years wearing out calculators working out geometry for CNC programs no cad  or cad cam at work.yes most of it ends up simple triangle to work out.

Offline Art K

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #151 on: June 27, 2018, 05:46:56 PM »
John,
The same friend gave me his copy of Mathematics at Work, Third Edition by Holbrook L. Horton guess I've got some studying to do. :) A few years back I returned to school & took algebra for the first time since HS, got B's. So I know I can do it if I apply myself.
Art

Offline jadge

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #152 on: June 28, 2018, 08:34:54 PM »
The little Aciera F3 is stiff enough for small things but it is very old and has some wear; I chose the depth of by the amount of vibration I could tolerate.  On a Bridgeport I'm pretty sure a single pass would work.

I wonder if the vibration was caused by an incorrect (too low) feedrate? When I started with my horizontal mill I managed to get the whole thing vibrating; and it weighs nearly two tons. Simply by increasing the feedrate the vibration went away completely.

Although I have a Tormach I'd have probably still made a cutter and used the horizontal mill. The only difference is that I would have used the Tormach to make the cutter, so relief is built into the CAD model. Although it's only cutting aluminium I would have hardened and tempered the cutter.

Andrew

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #153 on: June 28, 2018, 10:33:39 PM »
Thanks Andrew, I'm cleaning up the outsides of the Mastiff blocks with the vertical head right now. When that's done (tomorrow?) I'll put the overarm back on and experiment with feeds. I have made a few cutters in the past that I hardened and the cutting edges on those are probably sharper but it is just one more thing to go wrong...

Ramon, I've ordered the Garryflex blocks from Proops Bros, the local suppliers don't carry the very fine ones - thanks again for that tip. Also ordered some sheets of Klingersil for gaskets.

David

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #154 on: July 03, 2018, 01:36:22 AM »
Art, hang in there with the maths! Sue teaches maths at RMIT in Melbourne and some of the students that come in to their "drop-in" student support service haven't studied for 10 years or more and most of them get their diplomas and degrees. Having a local consultant can be very handy!

Andrew, I had a go at cutting a fin (space) in a single pass:



and it worked fine as long as the work was tightly clamped (took this as a reason to make 4 proper clamps for the vice). I haven't experimented much with feed rates. At the start of the cut (when the teeth were hitting the vertical face of the work) there was a bit of vibration but it smoothed out once the cut was established.

On Mastiff I've milled off the 90 degree corners on the heads and blocks to make the appearance a bit less brutal:



then reassembled everything, including fitting the piston rings:



Mastiff was very tight at the start but spinning the engine over with a cordless drill quickly started freeing it up. I won't do too much more of that until I've coupled up the lubrication system.

Next will be the ignition system bits.

David

Offline Roger B

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #155 on: July 11, 2018, 08:23:13 PM »
Looking good  :praise2:  :praise2:  :wine1:
Best regards

Roger

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #156 on: July 12, 2018, 01:49:04 PM »
Thanks Roger, its good to know someone is watching!

I haven't had any notifications of topics I'm following and didn't get one for your message, I'm having to look through the topics individually. Wonder if one of the old problems has recurred?

Currently I'm making the fiddly little bits for the contact breaker, more pictures soon. Temperatures in the workshop have been around 10 Celsius some of the time which does nothing for the enthusiasm, one little fan heater only just manages to keep my hands warm.

David

Offline Brian Rupnow

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #157 on: July 12, 2018, 02:26:10 PM »
Deltango--I look in on your build thread quite frequently. You are doing a lovely job.---Brian

Offline kvom

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #158 on: July 12, 2018, 04:05:13 PM »
For finish, did you consider powder coating?  What temperature do you expect to achieve?

Offline Ye-Ole Steam Dude

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #159 on: July 12, 2018, 04:11:09 PM »
It is a beautiful build and I am enjoying following along.

Have a great day,
Thomas

Offline zeeprogrammer

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #160 on: July 12, 2018, 04:33:19 PM »
Since I know nothing about this engine, I did a little googling.
It's a very interesting engine and you're doing a great job on it.  :ThumbsUp:

I'm looking forward to the run.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline jadge

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #161 on: July 14, 2018, 10:31:32 PM »
I'm following along as well.  :ThumbsUp:

It's interesting that the cutter was capable of cutting the fin (space) in pass. I suspect the vibration at the beginning is simply a consequence of the tooth geometry. Increasing the feedrate probably won't affect it. One thing I learnt early on in horizontal milling is clamp it down tight. I don't generally use the machine vice on the horizontal mill, preferring to bolt to angle plates, box cubes, or the table itself. The problem with a machine vice used in the normal orientation is that there is nothing reacting the cutting forces. Instead one is relying on friction between the work and vice jaw.

Andrew

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #162 on: July 15, 2018, 12:00:05 PM »
Thanks to all for the encouragement. Like Zee I'm looking forward to having the engine running (I'll be delighted if it does run!), I'll have to get myself a YouTube account for the videos.

Kvom - thanks for the suggestion of trying powder coating. As the engine is thermosiphon cooled it isn't intended to run very hot (obviously coolant <100C) but I won't know the actual temperatures until it's been run. Other Mastiff builders may be able to give more info. For bench running and display I probably wouldn't go for anything other than bare metal and I'm trying some Garryflex blocks as Ramon suggested. If I get motivated to build a boat for it to drive then powder coating might be a good option for corrosion protection.

Andrew, I agree about the machine vice not being the most secure, I didn't show a picture of the stop fitted at the other side to prevent lateral movement. Should have shown that!

Offline PJPickard

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #163 on: July 15, 2018, 01:50:39 PM »
Nice work and progress! I'd like to do this one day, its a nice design.

Offline deltatango

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Re: Len Mason's "Mastiff" - chewed from the solid
« Reply #164 on: July 21, 2018, 05:02:18 AM »
Thanks PJP, it would be great to see another one being built, I'm happy to help if you decide to start.

The contact breaker offers the last chance for making Al swarf on this build. The case was made from 2011 bar stock and turned and drilled in the collet chuck:



holes drilled and tapped for the posts to support the contacts and the slot milled for the fixed contact connections:



The cam was turned from 1/2" silver steel  and the flats milled in the dividing head:



A MS pillar supports the spring to hold the cap closed and has a thread for the advance/retard locknut. This was turned and threaded in the ER32 chuck:



then reversed and held in a threaded mandrel to turn a decorative taper:



I didn't take pictures of machining the little bits and pieces that go inside the case, here they are along with the cam drive shaft:



and in place on the engine:



More soon!

David