Small Trepanning Tool !

[JasonBModerator @jasonb]

[JasonBModerator @jasonb]

As the subject of trepanning crops up every now and again I thought this chap's video's which popped up as a suggestion on my Youtube would be of interests. Seems he does a good trade on trepanning out the middle of bits of steel bar judging by his other videos, The size of his chips should impress even Andrew this is a typical job.

 

And if you fancy making one for your mini-lathe here is how to do it.

 

Edited By JasonB on 27/05/2019 20:00:50

[PlasmaParticipant @plasma]

Blimey! Looks quite a job that.

[Anonymous]

Yep, seen his videos a while back and duly impressed. Man size machines too. I think one of his lathes is a DSG but good to see an old capstan lathe earning it's keep. Horrid materials, pricy as well. I'd expect that Inconel bar to be over £10k.

I'm thinking about doing something similar. For my traction engine cylinder liners I've been supplied with solid cast iron bar. Seems a real shame to drill and bore to end up with a 3/8" thick liner. I could drill on a circular pattern half way from each end, but that would leave a sharp inner part. I fancy having a go at a similar method to the video. I'll have to make one, as I can't find anything available commercially.

Andrew

[JasonBModerator @jasonb]

Sounds like a plan, I wonder if a TCT masonary core drill such as this could be reground to cut metal? Face grooving tool is the right shape but may only do 25% from each end.

There was an article a while back in ME that wire sparked the waste out of a TE cylinder.

 

Edited By JasonB on 27/05/2019 21:05:38

[Speedy Builder5Participant @speedybuilder5]

It just shows what a bit of old kit is still capable of. Did you notice the pile of old inserts on the turret ?

[Ron LadenParticipant @ronladen17547]

Posted by Andrew Johnston on 27/05/2019 20:59:22:

Yep, seen his videos a while back and duly impressed. Man size machines too. I think one of his lathes is a DSG but good to see an old capstan lathe earning it's keep. Horrid materials, pricy as well. I'd expect that Inconel bar to be over £10k.

I'm thinking about doing something similar. For my traction engine cylinder liners I've been supplied with solid cast iron bar. Seems a real shame to drill and bore to end up with a 3/8" thick liner. I could drill on a circular pattern half way from each end, but that would leave a sharp inner part. I fancy having a go at a similar method to the video. I'll have to make one, as I can't find anything available commercially.

Andrew

Not knowing much about it Andrew why do the engines have cylinder liners..? I am probably missing the purpose they serve but can a cylinder not be machined and finished to accept the piston without a liner..?

Ron

[Anonymous]

On a full size engine the cores required to create all the steam passages and ports within the cylinder block casting are incredibly complex. In the smaller model sizes it would be very expensive to replicate, and the scrap rate would be high due to the complexity. In addition how do you get the cured core sand out of the internal steam passages?

There are two versions of my model. The original design by Pete Filby and as modified by LSM. The LSM version has the passages cast in and uses thin liners, ~1/8", allowing precise positioning of the steam ports. In contrast the Filby design uses thick liners, 3/8", and has the steam passages machining into the outside of the liners along with some simple drilling of the cylinder block. This results in a simpler and cheaper cylinder block casting. Mind you I think the cylinder block for the Filby design is now over £500, I don't know what the current price for the LSM version is, but I'd sit down before looking.

Andrew

[Ron LadenParticipant @ronladen17547]

Posted by Andrew Johnston on 28/05/2019 16:41:37:

On a full size engine the cores required to create all the steam passages and ports within the cylinder block casting are incredibly complex. In the smaller model sizes it would be very expensive to replicate, and the scrap rate would be high due to the complexity. In addition how do you get the cured core sand out of the internal steam passages?

There are two versions of my model. The original design by Pete Filby and as modified by LSM. The LSM version has the passages cast in and uses thin liners, ~1/8", allowing precise positioning of the steam ports. In contrast the Filby design uses thick liners, 3/8", and has the steam passages machining into the outside of the liners along with some simple drilling of the cylinder block. This results in a simpler and cheaper cylinder block casting. Mind you I think the cylinder block for the Filby design is now over £500, I don't know what the current price for the LSM version is, but I'd sit down before looking.

Andrew

Thanks for the explanation Andrew I now understand the need for the liners.

Ron

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