Member postings for Roderick Jenkins

The DRO display on my mill has a problem with the top line of the X display. On switch on, the very top line of the display is missing. After being on for about 5 minutes the top line appears and all is normal. However, yesterday the problem persisted all day. I'm guessing there is a dodgy contact somewhere that used to sort itself out once the display warmed up but now it's permanent. The system is a good umber of years old and way out of warranty. Any advice before I start taking it apart and ruining it permanently?

Cheers,

Rod

Kind words. Thanks guys.

Spent a couple of hours making a starting dog that keys onto the drive side of the crankshaft

I think I've made it to drive in the right direction!

Rod

I need 4 rocker arms. The idea was to make them as a lump then saw it up into 4 pieces. First drill for the pivots

Then mill to half depth

and round off the protuberance

And slit

3mm hemispherical socket for the push rod end

Springs were wound in 22SWG piano wire at 10 tpi

I cut the valve seats with my trusty D bit valve seat cutter with a guide the same diameter as the valve stems

Valves retained with a collar and a 1.5mm E clip

A bit of hand work was required on the rockers to make them more presentable

The tappets also need a hemispherical seat - possibly the only acceptable use of an end mill in a drill chuck

The push round ends need to be hemispherical. I made a form tool by drilling a 2.9mm hole in some gauge plate, milling the excess away then hardening and tempering

One end threaded for adjustment and the other Loctited in place

A gratuitous picture (for Neil) of the hardened and ground dowel pin for the crank pin being trimmed

After Loctiting the cam shaft drive gear to the cams, the holes for the ignition triggering magnets need drilling. An elephant foot indicator found the peak of the central cam and the GHT Headstock Dividing Attachment was turned to give the -120 degrees and +39 degrees spacing

Drilled with my tool-post mill/drill

And that's pretty much all the mechanical bits of the engine done

Just need to wrestle with the carburation and ignition now

Thanks for dropping by

Rod

From the Office of National Statistics:

"Average regular pay growth for the private sector was 7.2% in September to November 2022, and 3.3% for the public sector; outside of the height of the coronavirus pandemic period, this is the largest growth rate seen for the private sector."

**LINK**

Rod

I think the Republican French were looking for a unit about a yard long that didn't rely on the length of a King's arm. I wish they had chosen a length for the metre that resulted in the acceleration due to gravity as 10m/s/s rather than the generally accepted average figure of 9.81. It would have made 'O' level physics much easier (in the days before electronic calculators).

Rod

That's a bit didactic. Not best modern practise perhaps but people have been using Dewhurst switches safely and successfully for the last 70 years. The contacts may get a bit pitted after half a century - a bit like putting a plug into an un-switched socket.

Anyway, nice lathe Dell. You'll enjoy that.

Rod

+1. Almost all my turning is done with ccgt inserts (and cheap ones at that)

Rod

I like the design from Hemingway

**LINK**

Rod

Yes, I've not seen orthogonal sections from our usual suppliers. However, it seems to be available e.g.

**LINK**

I wonder if it is more popular in industry these days due to CNC operations. I'd certainly choose it in preference to EN3 for machining.

Rod

The valve guides are brass. I turned the OD for a press fit in the head in the 3 jaw and then parted off, dialled in the 4 jaw and drilled and reamed through

The returned to the 3 jaw (now that concentricity is not so important) to cut the spring seat and taper

My valves are stainless steel turned down to a 5/32" shaft and then grooved for a 3mm E clip

The heads are relieved to 1/8" and the seats turned to 45 degrees. They will be ground in later

4 valves, all very nearly the same

Rod

This is my favourite piece of swarf . While boring out a pulley it decided to feed itself through the lathe spindle and down into the swarf bucket which was on the floor next to the lathe.

Rod

I think the RCEXL system ( I havn't played with it yet) uses a pair of sensors that respond to different poles of the magnet so one magnet is installed N facing the sensor and the other S facing.

Rod

Ian,

How frustrating. It looks like Minimag may have a solution:

Minimag

Cheers,

Rod

Clickspring on YouTube has made some

Pistons are straightforward. Turned on the lathe then transferred in the chuck to the mill for drilling and reaming the hole for the gudgeon pin

Then back to the lathe for hollowing out

then back again to the mill to cut the relief for the little end of the con rod

As per Jason's suggestion, the crank shafts will be keyed

3mm slot drill

That seems to work

The cylinder studs are 4" long and I need 8 of them so a bit of mass production called for. My original lathe backstop was designed for holding thin parts square in the chuck. The depth is adjusted by a 40tpi thread in the Morse Taper. It won't go anywhere near accommodating a 4" stud. An hour's work made a new backstop with some 1/2" BSF studding which will take longer lengths.

The O rings are the same as I used to great success in my Farm Boy - rather larger cross section than specified but they are what I've got

It's beginning to look like an engine. The pistons go up and down and the cam gears mesh

Thanks for looking in,

Rod

I scanned the TC articles for a previous discussion. They are in my Photo albums:

Tubal Cain Governor Articles

Rod

Edited By Roderick Jenkins on 29/01/2023 09:13:16

My interpretation is that NASA are admitting that in the past this has not necessarily been the case. The rather good film "Hidden Figures" emphasises how recent these issues are and that NASA did do a little bit to ignore racial origins.

Rod

Ian,

I sent you a PM.

Rod

Thanks Jason. I think that's the way forward. I'm using a hardened dowel pin for the crank pin so not an option there but fortunately the crank pin is gripped quite well. It is the other 2 that can be less firm and they will be un-hardened silver steel.

The CNC mill is fully 3D with Fusion 360 but, illogically, it seems less trouble to use the manual mill for fairly simple shapes.

Cheers,

Rod

John, I have sent you a PM.

Rod