I somehow missed this video - only when watching the next did I realise I had missed one. Fantastic work - this is surely model engineering at it's finest. Very well done. You have the patience of a saint.
...Had to come back to this video as I am coincidentally remaking a piston for my RedWing hit n miss engine that i failed to get running a few years ago...i know that my aluminium piston is made wrong, because i made it. Although I could find generic piston tolerances anywhere online, i could never find the thermal expansion tolerance that you so eloquently explained. Thanks for sharing this sacred knowledge. Your engine looks great.
Hi. I made two hit n miss engines and they run really cool. I think the cylinder/piston differences were 1 or 2 thou for a 1" dia piston from memory. I covered the making of these pistons in some earlier videos which might be helpful. I hope you get your RedWing sorted soon. Hit n miss engines are amazing! Cheers Andrew
Respectfully, FYI, aluminum pistons are tapered. The top expands more than the skirt so you actually need 2 measurements when making aluminum pistons. Your math was correct for the TOP of the piston. The skirt clearance is "generally" only .001" per 1 inch diameter of the piston because its much cooler than the top of the piston. A real mind blower is that automotive pistons are also oval...not round....cam ground... because the wrist pin area is hotter and expands more. Enjoyed your video....thanks.
A lot of maths in the making of your pistons. So many opportunities to get the numbers wrong! They look good and fit well. I particularly liked the drilling out of the pistons. When the chips started flowing out of the gudgeon hole it looked like some early 20th century iron works. Sounded like you had a drop of rain at one point too ⛈🌧☔
Thanks Tim. I think I was incorrect in assuming the engine could get to 200 degrees C. More likely to be 100. Still probably wise to stick with cast iron though. Yeah, speeded up the video reminded me of a lava flow running out of the hole! Yeah, a good test to see how well the roof has been constructed! No leaks! Cheers Andrew
Hi Alex. I think some of the more modern alloys have a similar thermal expansion to that of cast iron, but I don't think the aluminium I have is anything special. An interesting subject nonetheless and maybe really relevant in relation to older motorcycle and car engines. Cheers Andrew
The rule of thumb for aluminium piston in steel/iron bore is make the piston 2 thou per inch less than the bore. I have made a few model engines to this and never had any issues.
Yeah - I agree. I too have made a few ic engines using aluminium pistons without issue. The issue here is that this is a high revving engine, so temperatures will be higher. Jerry Howell refers to thermal expansion being a potential issue. Over the past few years I've learned to stick to the original design recommendations. Cheers Andrew
You have got better and better since starting posting videos, it’s a real inspiration to keep going and to learn along the way. And gives me confidence as well not being a qualified engineer.
Ha ha Dave - you could be right! I've just 'google' car engine temperatures and I think they only get to something like 100 degrees C. But I also think it was wise to stick to the drawing. All the best. Andrew
Hi Andrew, nice work on the pistons. In the plans does it mention what aluminium is used for the pistons? Not all aluminium has the same expansion/wear rates. Regards Kevin
Thanks Kevin The drawings recommend cast iron rather than aluminium, specifically due to expansion issues. The 6082 t6 aluminium I have has a thermal expansion coefficiant value of 24 x 10 to power of -6 as outlined in my calculations. I understand that aluminium types have evolved over recent years and some have lower thermal expansion values. Not sure which those are though and if they are readily available in the UK. Over the past couple of years I've learned that it's best to stick to the drawings 😪 Cheers Andrew
good video, you need to wear those piston rings in for better compression before testing. and its better to make a piston half a thou to small then a half a thou to big, otherwise you risk jamming the piston when to big. cheers ben.
Hi Ron. I spent all of my career messing around with computers which was extremely interesting. My father was an associate member of the Institution of Mechanical Engineers but died too early. If he had lived on I guess he would have influenced my career choice. 5 years ago I had little knowledge of engineering and bought my first lathe and mill. I've always enjoyed making and fixing things and I've found model engineering real fun. It's never too late to learn new things. All the best. Andrew
I somehow missed this video - only when watching the next did I realise I had missed one. Fantastic work - this is surely model engineering at it's finest. Very well done. You have the patience of a saint.
Thanks Kevin, but you should see me off-camera. 🤣
Nicely done. Cast iron machines so nicely, but the dust!
Thanks mate! My wife always knows when I'm machining cast iron 🤣
...Had to come back to this video as I am coincidentally remaking a piston for my RedWing hit n miss engine that i failed to get running a few years ago...i know that my aluminium piston is made wrong, because i made it.
Although I could find generic piston tolerances anywhere online, i could never find the thermal expansion tolerance that you so eloquently explained.
Thanks for sharing this sacred knowledge.
Your engine looks great.
Hi. I made two hit n miss engines and they run really cool. I think the cylinder/piston differences were 1 or 2 thou for a 1" dia piston from memory. I covered the making of these pistons in some earlier videos which might be helpful. I hope you get your RedWing sorted soon. Hit n miss engines are amazing!
Cheers
Andrew
ANDREW
Very nice work.
It’s always a pleasure for me to watch your videos. Already looking forward to watching the next one.
BFN
OL6162
Thanks OL. I've just made my sister-in-law a keyring with a mini logo on it. The engraving machine is awsome!
Cheers
Andrew
Nice one Andrew. Tha pistons look great.
Regards.
Steve.
Thanks Steve!
Another great video Andrew thanks for sharing
Thanks Matt! 👍
Nice work Andrew!
Thanks Tony!
All the best.
Andrew
Very nicely done
Excellent
Thanks Chris!
Great result Andrew - those are quite intricate pieces.
Thanks Stuart!
Respectfully, FYI, aluminum pistons are tapered. The top expands more than the skirt so you actually need 2 measurements when making aluminum pistons.
Your math was correct for the TOP of the piston.
The skirt clearance is "generally" only .001" per 1 inch diameter of the piston because its much cooler than the top of the piston.
A real mind blower is that automotive pistons are also oval...not round....cam ground... because the wrist pin area is hotter and expands more.
Enjoyed your video....thanks.
Very intertesting - thanks for taking time to explain.
Cheers
Andrew
A lot of maths in the making of your pistons. So many opportunities to get the numbers wrong! They look good and fit well. I particularly liked the drilling out of the pistons. When the chips started flowing out of the gudgeon hole it looked like some early 20th century iron works. Sounded like you had a drop of rain at one point too ⛈🌧☔
Thanks Tim. I think I was incorrect in assuming the engine could get to 200 degrees C. More likely to be 100. Still probably wise to stick with cast iron though. Yeah, speeded up the video reminded me of a lava flow running out of the hole! Yeah, a good test to see how well the roof has been constructed! No leaks!
Cheers
Andrew
From a motorbike/scooter engine viewpoint l found your materials expansion examples most usefull. Thanks for that. Alex norfolk.
Hi Alex. I think some of the more modern alloys have a similar thermal expansion to that of cast iron, but I don't think the aluminium I have is anything special. An interesting subject nonetheless and maybe really relevant in relation to older motorcycle and car engines.
Cheers
Andrew
The rule of thumb for aluminium piston in steel/iron bore is make the piston 2 thou per inch less than the bore. I have made a few model engines to this and never had any issues.
Yeah - I agree. I too have made a few ic engines using aluminium pistons without issue. The issue here is that this is a high revving engine, so temperatures will be higher. Jerry Howell refers to thermal expansion being a potential issue. Over the past few years I've learned to stick to the original design recommendations.
Cheers
Andrew
Hi Andrew, you should take a look at how to make clupet piston rings at peters railway
Hi Rich. Very interesting. A great idea for larger rings.
Cheers
Andrew
Very nice work.
Thanks for sharing the process.
Take care, Ed.
Thanks Ed!
Cheers
Andrew
Nice one !!
👍 cheers Alan!
Another great outcome Andrew. Coming along nicely now. Regards from Australia
Thanks Dave.
I hope all is okay at your end.
All the best.
Andrew
You have got better and better since starting posting videos, it’s a real inspiration to keep going and to learn along the way. And gives me confidence as well not being a qualified engineer.
Hi Derek. Glad you like the videos. Just good fun at the end of the day.
All the best.
Andrew
Very hard to do mate. I will have to pick up tips from you in the future. I have been out of the trade for years!
Thanks Dermot - just remember, I am certainly no expert!
Cheers
Andrew
Nice job Andrew. I'd also go with the Fe pistons as per the plan. However, I would think if your seeing 200 C degrees you've got serious issues!
Ha ha Dave - you could be right! I've just 'google' car engine temperatures and I think they only get to something like 100 degrees C. But I also think it was wise to stick to the drawing.
All the best.
Andrew
As you say, a pretty complicated task. I doubt that I would ever have had the patience to become a competent engineer. Best wishes as ever.
Hi George. I certainly wouldn't say I was a competent engineer but it's good fun trying to be one.
All the best.
Andrew
Hi Andrew, nice work on the pistons.
In the plans does it mention what aluminium is used for the pistons?
Not all aluminium has the same expansion/wear rates.
Regards
Kevin
Thanks Kevin
The drawings recommend cast iron rather than aluminium, specifically due to expansion issues. The 6082 t6 aluminium I have has a thermal expansion coefficiant value of 24 x 10 to power of -6 as outlined in my calculations. I understand that aluminium types have evolved over recent years and some have lower thermal expansion values. Not sure which those are though and if they are readily available in the UK. Over the past couple of years I've learned that it's best to stick to the drawings 😪
Cheers
Andrew
good video, you need to wear those piston rings in for better compression before testing.
and its better to make a piston half a thou to small then a half a thou to big, otherwise you risk jamming the piston when to big.
cheers ben.
Thanks Ben. Fair point about running the rings in first.
Cheers
Andrew
How much does one of your pistons weigh?
I'm guessing you're retired (and clearly enjoying it). Were you an engineer in your previous incarnation?
Hi Ron. I spent all of my career messing around with computers which was extremely interesting. My father was an associate member of the Institution of Mechanical Engineers but died too early. If he had lived on I guess he would have influenced my career choice. 5 years ago I had little knowledge of engineering and bought my first lathe and mill. I've always enjoyed making and fixing things and I've found model engineering real fun. It's never too late to learn new things.
All the best.
Andrew
@@learningturningmetal Well you've come a long way in 5 years!
👍😎👍
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