Benson's Vertical Steam Engine

[b.lindsey]

The base looks great John, pretty intricate part as you say!!  Still following along on this new project.

Bill

[J.L.]

Merry Christmas Bill.
Thanks. Good to have you looking over my shoulder.

If this column had a pommel on the end the way it is set up now on the milling table, it would look like the barrel of a 24 pounder navel gun. I got the idea of clamping the column to an angle plate in Anthony Mount' book 'Historic Engines Worth Modelling' Tee Publishing.

The holes will be tapped #1-72 for a guide bracket.

[kvom]

Based on the plans shown underneath the column, plotting the profile points wasn't the hard part of setting up the CNC lathe in CAM.  Getting the proper tooling set up for cutting the details would take some careful thought.  Your guy did an awesome job.

[Jasonb]

I would have thought it only needed a left hand and a right hand tool to turn it all or you could even reverse it in teh lateh part way through and just use one tool.

You are off to a good start John, it's a nice looking engine when done

[J.L.]

Thank you gentlemen. I'll pass the compliment along to the machinist.

A lot of fussing was done with the entablature shown chucked here in the 4-jaw. I could not get that rectangular shape centred until I took the part to the milling machine and took a stab at where the centre of the base would be with a center drill. Mounting the part with the dead center in the tailstock on the lathe as a guide worked for me.   I'm not out of the woods yet though with this part.  It's a casting that will require a lot of milling, hole drilling and tapping.

The entablature is perhaps the linch pin of this project. It supports all the upper elements of the machine - the bearings,  the flywheel, the governor and gears, the eccentrics and the crank.

Let's get it right.

[crueby]

For centering that part, wouldn't it have been better to reverse two of the jaws to hold the long direction on the part on the outer steps? That would leave room above the ways without the jaws hitting. I've tried chucking the way you did, and also had big problems adjusting the position. Given the narrow side dimension, there is not enough room to reverse all four jaws, but doing two and bringing in the others to hold the part from the sides should work.

[J.L.]

Hi Chris,

The horse is already out of the barn with this setup Chris, but I like the way you think. I agree. At least with two reversed jaws, you could move back an forth with two chuck keys. But where is centre? You can't use a dial indicator - the casting is not round.

When I said I took a guess at centre, what I meant was I used a V centre finder and scribed several lines across the bottom of the base. The centre was in there somewhere. 

We'll see the result shortly of the efforts.

Thanks for the suggestion Chris.

John

[kvom]

Measuring the dimensions of the casting and comparing with the final dimensions per plan gives a good idea of how much leeway is available in locating the center.  At least from the photos you seem to have found an acceptable point.

[J.L.]

Hi Jo,
Yes, I'm not dead centre, but I'm close. Here's the result so far...

[10KPete]

Lookin' good, John!   

Pete

[J.L.]

Thanks Pete,
Here's the setup for milling the ends of the entablature. At first, I had only the hold downs keeping the part in place. They failed and the part slipped to the left 
There was more material to be removed so the resulting dig-in could be faced off.

You now see four flat clamps butting up against each of the four corners of the rectangle to prevent future twisting. It's amazing just how much pressure a cutter applies to a part when cutting. You have to anticipate all possibilities in the set ups I guess. You can't assume anything!

[Flyboy Jim]

John,
That's an interesting fixture holding the part.  Did you make that just for this part?

Jim

[J.L.]

Hi Jim,
No, the t-slotted table is an accessory item for the Unimat Lathe. I have found it so useful. You can clamp it directly to the milling table and have all kinds of options open to you.

Best accessory I purchased for the Unimat.

[J.L.]

Things are moving along slowly but steadily.
The first photo shows the entablature with a first coat of primer. I find that the high build/filler primers cover a multitude of sins. This casting has pin hole in it and of course all of my file marks. It still is not a pretty site, but the high build will smooth things out after about two more coats. You can see file marks where I've been levelling the primer!

The second photo shows a bracket that has just been profiled with the rotary table. There will be a lot of tricky little such pieces in this project. The profile is not symmetrical, but it's close. I've been used to using brass for such pieces, not steel.

[J.L.]

Here is that steel bracket being installed.
If I did not have the MicroLux Tapping Fixture, I'm sure I'd be ordering #0-80, #1-72 and #2-56 taps by the gross. I can't imagine using a hand over hand tapping yoke.