Long Bar Holding Option

[MaverickNH]

@GeneT45

I have had absolutely ZERO grabbing since I started using ally inserts on brass. The edge is sharp and cuts nicely. CCMT/CNMT always seem to want to grab when I use them, even when on centre.

The WD40? it keeps things cooler and further lessens potential for grabbing.

@MaverickNH

Have you determined your order of operations yet?

Will you be turning the bore first? if so, you will need a fixed steady rest and once bored, you could, indeed, consider @Charles scozzari option of a plug in the bore to centre on with a live tailstock centre.

On a Southbend, I had first turned the breach end of the cannon, reversed and clamped in a sleeve, then turned the muzzle, then drilled and bored the bore last.

Pictured here https://www.hobby-machinist.com/threads/brass-mini-cannon-first-firing.114139/

 

[MaverickNH]

Concur with order of operations. However, instead of making a plug for use witch a live center, consider getting a live center with interchangeable tips:

View attachment 505934

An interesting option. Is there an optimal live center to stock ratio range to consider? Do the tips in this set match a standard #1 - #5 center drill set range?

I just noted my LMS Steady Rest is 1” capacity and my stock is 1.25”, so I might need the 1-2” capacity steady rest. While my stock pictured is plenty long for a 5” cannon, I was thinking I could part off the section marred by the Steady Rest.

 

[brino]

I do NOT see the need for a steady/follower rest as long as:
1) the OD profiling operations use the live centre, and
2) you're never cutting it down to a thin section that will allow it to flex.

I would follow the same order of operations you did on the SB.
Drill and bore last.

I cut brass dry.

I would recommend a zero-rake HSS tool like Chris (Clickspring) uses for his gyroscope.
The beauty is that it can cut in multiple directions and therefore help blend the external shape.
Here's a link to the video at the intro to that tool:

(but you may want to watch the entire thing, Chris does amazing work!)
(also the little brass plug that Chris only uses to layout the recess is really much like the plug that @Charles scozzari mentions above)

Have fun and be safe!
Brian

 

[MaverickNH]

I do NOT see the need for a steady/follower rest as long as:
1) the OD profiling operations use the live centre, and
2) you're never cutting it down to a thin section that will allow it to flex.

I would follow the same order of operations you did on the SB.
Drill and bore last.

I cut brass dry.

I would recommend a zero-rake HSS tool like Chris (Clickspring) uses for his gyroscope.
The beauty is that it can cut in multiple directions and therefore help blend the external shape.
Here's a link to the video at the intro to that tool:

(but you may want to watch the entire thing, Chris does amazing work!)
(also the little brass plug that Chris only uses to layout the recess is really much like the plug that @Charles scozzari mentions above)

Have fun and be safe!
Brian

The breach end does have a narrow section at the breach end - note there's a step under the trunnion ring not visible where the diameter increases to seat the cannon in a match step on the ring's inner diameter.

Perhaps I can turn the 1.25" diameter down to fit my 1" Steady Rest just by the jaws as shown in my 1st post, then reverse to mount the Steady Rest?

 

[brino]

Perhaps I can turn the 1.25" diameter down to fit my 1" Steady Rest just by the jaws as shown in my 1st post, then reverse to mount the Steady Rest?

That seems reasonable.

Could you make new fingers for the steady rest or modify the existing ones to give you that little extra?

Brian

 

[VicHobbyGuy]

Could you make new fingers for the steady rest or modify the existing ones to give you that little extra?

Yes.

 

[MaverickNH]

Yes.
View attachment 505993View attachment 505992

It looks like you machined out the brass fingers a bit closer to the points compared to mine. A 3/8" mill fits pretty good. Would that be the way to go? I should get 1.25" to work OK - is yours up to 1.5"?

 

[ChazzC]

That seems reasonable.

Could you make new fingers for the steady rest or modify the existing ones to give you that little extra?

Brian

Not helpful here, but I considered this problem when I purchased my steady rest from LMS, got the 1” - 2” version and made extra long fingers (and added bearings) so to make it 0” (ish) - 2”:

 

[VicHobbyGuy]

It looks like you machined out the brass fingers a bit closer to the points compared to mine. A 3/8" mill fits pretty good. Would that be the way to go? I should get 1.25" to work OK - is yours up to 1.5"?

"Machined"=rough work with a file. I think the casting opening is about 1.5" ID ?

 

[GrifterGuru]

I went a slightly different way as regards steady rest.... Maybe a little OTT, but I acquired a Myford ML7 steady with a modified foot that allows it to fit the 7x bedway. Covers everything I will ever need.

I have since acquired an unmodified one that I intend to modify myself. Other than modifying the fingers to have a bearing rather than a brass tip, and modifying the foot, I have no need to modify it beyond what has already been done..