Taper Turning Attachment for Myford ML10 Patterns

[Meldonmech]

Hi Guys,
              Where possible I will be making this project from aluminium castings. The slide and carriage will also be aluminium, however the carriage will have Delrin bonded onto the sliding faces. This material has excellent wear properties, and the attachment has a very low sliding duty cycle. To cast the main bracket I have made a larger crucible, and increased the height of the furnace by four inches. The furnace has been relined with a castable refractory to withstand 1600c., and it has been drying out for a month. I gave it a gentle low heat firing for 15 min this week, and am now waiting for some decent weather, as I only cast outdoors.

                                               Cheers  David

[Pete.]

Nice - we love a good castin'

Doesn't seem to be any draft on the ribs, or is it just the angle they are photographed from?

Also, I didn't think it was possible to bond Delrin to any great holding strength.

[mattinker]

Why the Delrin? It's difficult to bond, Al to steel have very good sliding qualities and a low wear rate.

Regards, Matthew

[Rob.Wilson]

Got brew,tad's and crisps ,thats me tuned in 


Rob

[vtsteam]

Looking forward to this! 

[Meldonmech]

Hi Guys,   Thanks for your comments.
 Pete, there is draught on the ribs, as you suggest it is photographic distortion. I have only used Delrin for circular bearings and was unaware of it's poor adhesion properties. I will use a mechanical fixing if I use Delrin.
Matthew,  Al to steel would be a much simpler combination, will seriously consider.
Rob,  I will be making a loose piece for the step in the large bracket, to aid the moulding when ramming the drag.
        This bracket is the largest casting I am about to attempt, and I am not sure where to position the in gate, and out gate, to ensure a satisfactory pour, can you advise.

                                                  Cheers  David

[hopefuldave]

I like that taper attachment, very similar to the one on my Holbrook. Will you be fitting a screw adjuster for the "opposite" on the sine bar too? I think the.Monarch 10EE had a graduated micrometer collar on its taper attachment, might be worth a Google (and doing the geometry!)

I'm very rusty on casting, so take with a pinch of salt, but were I  casting that I'd probably put the in gates where the ribs meet the vertical mounting plate (3 of 'em) and run a tapered runner parallel with the mounting plate, below the level of the casting so it filled from the bottom. I'd put risers at the top of each rib/plate junction and vents at the far ends, the far ends would probably cool fastest (most surface for mass of metal) so the ' corner' is where the worst shrinkage would be, thus where you need a nice fat riser or three to supply more metal.

I may be very wrong though, I often am...

I have the promise of a nice 200 litre! steel drum so I may soon have.the beginnings of a furnace and the prospect of some ally casting, I'd like to make a few replicas of fittings on the Holbrook (eg a toolbox bracket aping the one for the collet box) and perhaps a body for a headstock dividing attachment (to go outboard of the headstock).

I think I'll try lost foam casting first, as my woodwork's not as good as your, not nearly!:

Does anyone have links to a simple waste oil burner, one that doesn't need lots of high-pressure air or oil pressure?

Dave H. (the other one)

[Pete.]

I have a freshlycleaned and re-assembled 10EE one right here on the bench. If you'd like any measurements off it just holler.

[Rob.Wilson]

Hi David

Are your flask large enough to have runners and a gates down each side of the casting ? so that you could gate into the bracket face were it bolts to the lathe bed and into the section were the guide is mounted .


Rob

[Meldonmech]

Hi Rob,
            Must check my flasks, have a feeling things may be a tad too tight, may have to make a new flask.


                                                                   David

[Meldonmech]

  Making the Castings
                                                 A new crucible had to be made, capacity around 2 litres. This led to the furnace having to be increased in size by 4 inches. When I tried the main bracket pattern in my largest flask it was too small. I made a new flask and all went well until I tried to lift it, and realized I had completely under estimated the weight of the damp sand. The flask had used two 25kg sacks of sand. I had to get my other half to help lift ,and carry it to the pouring position. Having only melted a max. of 1L of aluminium in the past, it took nearly twice as long to melt 2L. I provided one runner and two risers in the mould, note the positions on the casting, since there was no shrinkage on the casting. I made sure the melt was on the hot side before pouring. The  casting is not perfect, but I am well pleased with the results at my first attempts at a casting of this size. I think it will clean up nicely, it weighs in at  5.5 lbs.
                                                                                                                Cheers  David

[Rob.Wilson]

  well done David


Looks a good sound casting    ,looking forward to seeing it machined up .


Rob

[Pete.]

I'd be pleased with that!

[doubleboost]

Great job with the casting
I made a extension piece for mu furnace as well
It looks to be a good casting
John

[Meldonmech]

Hi Guys,

             Thanks for all your comments and interest, seems like we have a little casting club. First time I have been able to get outside and do any casting this year.
                                                             Cheers David
                       

[Meldonmech]

I started on the slotted link arm, milling the side square to provide a datum, then machined the bottom flat. Next there was a problem holding the casting in order to machine the top, I made a rectangular hardwood boss which I screwed to the casting base using two holes I had drilled and tapped in positions where they would be lost when machining the slot. This proved to be a satisfactory method of holding the casting. The top of the casting was machined and the slot marked out. The boss was then attached to the top surface and the casting held in vice while the inner surface of the side was machined parallel. The casting was then held by the side while the slot was cut. The holding of this little casting may seem complex, but that is how I found it, and I didn't really expect it. Had I foreseen it I could have added a holding boss to the pattern.

                                                                          Cheers David

[Meldonmech]

 
               Made some progress machining the Main Bracket.

   PIC 250  Fettling the edges.
          251  Supported on 123 blocks beneath and clamped
          252  Fly cutting the slider face, at 1000 rpm, a fine feed and light cuts using a honed round nosed cutter.
          255  Keeping everything square to cut the front face.
          257  Guard on and chips flying everywhere.
                                                                                    Cheers  David

[Meldonmech]

    Hi Guys,
                                   The first set of pics show my set up for drilling and spot facing the mounting holes. When I came to mark out and drill the mounting holes on the lathe, I had a bit of luck, the lathe position was directly opposite an opening workshop window. This enabled me to work from outside without moving any workshop machinery. The pics show the levelling and clamping for spotting through and drilling and tapping the 10m holes for hex hd screws.
                   There was a vertical taper on the bed the bracket was packed out with feeler gauges in the mounting screw positions to ensure a level plane with lathe bed, and two packing pieces made.

                                                                                                                   Cheers David