Postman Cometh Part 2

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Postman Cometh Part 2

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  • #201008
    Nick_G
    Participant
      @nick_g

      .

      Delivery from the postman again of a set of castings from Stuart for their No.4 engine.

      Think I will start from the bottom and work up.

      That Jason bloke thinks I should have it finished by this coming weekend including the paint drying. wink

      But first I will have a cup of tea. laugh

      Nick

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      #31090
      Nick_G
      Participant
        @nick_g

        Build progress of Stuart No.4

        #201009
        JasonB
        Moderator
          @jasonb

          Can't you multi task and drink tea while machining? Just don't pick up the cutting fluid by mistakesmile p

          #201011
          Bowber
          Participant
            @bowber

            That's were CNC comes in for the home shop, drink tea while creating the program on your computer and then have another cuppa while watching the CNC bugger up your castings.

            Order replacement castings then repeat. (well that's what I did anyway!)

            Steve

            #201012
            GarryC
            Participant
              @garryc

              Wow looks good Nick, look forward to following along…

              Garry

              #201014
              nigel jones 5
              Participant
                @nigeljones5

                that there flywheel casting looks a bit ropey !

                #201018
                JasonB
                Moderator
                  @jasonb

                  Funny you should say that, it does look like most parts have been shell cast and have a very smooth finish, cylinder looks to be sand cast and maybe balast for the flywheel?

                  #201028
                  Nick_G
                  Participant
                    @nick_g
                    Posted by fizzy on 19/08/2015 17:48:33:

                    that there flywheel casting looks a bit ropey !

                    .

                    You are right. In the photographs it does look so.

                    I will go and have a nosey at it and let you know.

                    Oh and that cup of tea also turned into a 2 hour snooze, which means I will not sleep tonight now.! indecision

                    Nick

                    #201038
                    Ady1
                    Participant
                      @ady1

                      A moment of empathy for the postman might be appropriate

                      Is that flywheel oval shaped?smile p

                      Edited By Ady1 on 19/08/2015 20:17:09

                      #201039
                      Nick_G
                      Participant
                        @nick_g

                        .

                        Had a look at the flywheel.

                        It's OK smiley Just thin flashing and the halfs are aligned reasonably well.

                        Phew.! Nick

                        #201042
                        Nick_G
                        Participant
                          @nick_g
                          Posted by Ady1 on 19/08/2015 20:15:25:

                          A moment of empathy for the postman might be appropriate

                          Is that flywheel oval shaped?smile p

                          .

                          Well actually it was a courier. laugh But me being an old fashioned sort of guy I remember when the postman delivered everything. Even remember as a kid that it was not unknown for a postman to deliver on Christmas day.!

                          Oval flywheel.? …………. Bugger off you.!!! winkwinkcheeky (but I suppose it will be to some degree)

                          Nick

                          #201230
                          Nick_G
                          Participant
                            @nick_g

                            .

                            So we make a start. smiley

                            The boxbed had it's worst high spots filed off and was milled with a fly cutter on both sides.

                            Similar was done with the sole plate on the bottom. However I would have had to make special mounting brackets / plates to do the top surface due to its shape and small size. I could have made several passes on it with moving the mountings but I ideally wanted to make the cuts on it in a single pass.

                            So it was mounted for the top face cuts in the 4 jaw on the lathe. I had to be careful to tighten it enough so that it would not move under cutting yet not so tight that it introduced a twist in it or even fractured it. sad However it seemed to go all OK producing a nice flat and good finish.

                            Nick

                            #201258
                            GarryC
                            Participant
                              @garryc

                              Hi Nick

                              Great to see you've made a start, I'm quite envious of that nice Lathe you have..! Also interested to see what to me anyway looks like a 'button' profiling tool in the milling cutter – I've not seen anything like that before. Looks like it does a nice job..

                              and look forward to seeing the next update..

                              Cheers

                              Garry

                               

                              Edited By Garry_C on 21/08/2015 12:22:18

                              #201522
                              Nick_G
                              Participant
                                @nick_g

                                .

                                I found a lazer edge finder very useful for getting some 'sort of' ref points on the sole plate I say 'some sort' because although Stewart have revised the drawing for this part concerning the bearings the 4 studs and nuts that hold it to the boxbed would also not work.

                                .

                                Next was the standard. I made a mandrill to make a press fit to the bore of the casting and drilled and tapped M6 threads in it.

                                .

                                This was so that I could machine the feet of the standard 'reasonably' true to the bore.

                                This went all OK with a newly sharpend bit in the tool holder considering the unsupported legs of the standard and I was happy with the finish. I did however change the live centre from the one in the image to a more heavy duty one as I did not want to knock the backside out of my best one on the interrupted cuts.

                                Again it became apparent that the casting was slightly undersize length in order to clean the faces up. sad This is an important length.! I will be able to recover this though by making the cylinder bottom slightly thicker to compensate.

                                Small video here :- **LINK** It sounds like a steam engine already making the interrupted cuts. wink

                                .

                                The standard was reversed and mounted onto the face plate. I was sure this setup would need beefing up for facing and boring.

                                Since the above image was taken I made a few tentative cuts into the bore with a 16mm solid carbide boring bar that I snaffled on ebay for a sinch. (nobody else bid.) I really am impressed with it. smiley The bore cleaned up after 20 thou. So it seems the mandrill did its job of finding the average of the rough cast bore.

                                Made a few passes after the bore cleaned up and measured each of the bore ends with a telescopic gauge. To my surprise there was only 1/2 thou difference over the 2 3/4 inch length with a really nice finish. I will bore the rest out today to 1 1/8th and see if I can cock it up. frown

                                Another short video clip here :- **LINK**

                                When I come to make the cross head how much undersize do you think I should aim for relative to the 1 1/8th of the standards bore.?

                                More later I hope. smiley

                                Nick

                                #201524
                                JasonB
                                Moderator
                                  @jasonb

                                  Its not a size I would measure, just feel the fit of the two parts, probably less than a thou if measured. Worth lapping the trunk guide before you make the crosshead.

                                  #201636
                                  Nick_G
                                  Participant
                                    @nick_g

                                    .

                                    #201972
                                    Nick_G
                                    Participant
                                      @nick_g

                                      .

                                      Decided to make the cross head tonight.

                                      I used some EN8 bar I had against the piece supplied as it would have been more fiddly to work with the shorter piece.

                                      Drilled and tapped the hole to take the piston rod.

                                      Over to the mill to carve out the shape. I had to do this in a few passes as the correct size one was not sharp.! (I need to spend some coins on some decent ones)

                                      And here we are. ……. Although I do need to drill and ream the 1/4" hole across it to take the conrod gudgeon pin. I may make this a little larger than 1/4" and bush it. Then make the hole in that 1/4"

                                      That's it for tonight. Been a long day with an early start. If I continue I am likely to make a dogs-danglers of it. frown

                                      Nick

                                      #202563
                                      Nick_G
                                      Participant
                                        @nick_g

                                        .

                                        Decided to progress with the bearings and the work on the solepate to accept them.

                                        I machined them in the pair so as to keep them as close as possible to each other. The downside to this is that if I dropped a clanger I would have to buy 2 castings not one.

                                        They came out OK as near as dammit identical. smiley

                                        I attacked the soleplate to accept them.

                                        Nice snug fit. smiley

                                        Next I have to mill across the soleplate the correct width and depth so they drop in. (hopefully nice and snug.)

                                        Doing this stage has taken me far, far longer than I thought it would.! But I have had a nice relaxing day machining, brew drinking, bacon buttie chomping and throwing in the occasional 'move' to Smooth FM. blush Mate also came round on his mint Norton Commando wanting to know could he use my machines soon to make parts for a turbo 1100 Kawasaki he is building.

                                        Nick

                                        #202689
                                        Nick_G
                                        Participant
                                          @nick_g

                                          .

                                          Pressing on I cross milled the soleplate and fitted the lower bearing halves.

                                          So onto the bearing caps.

                                          After milling the bottoms and dressing on some abrasive I heated them and then tinned them with electronic cored solder.

                                          Back to the blow torch and the were joined together.

                                          Over to the lathe and into a 4 jaw chuck. I used a dial indicator and a laser finder in the tailstock to make the best 'guesstimate' of certre-ish alignment.

                                          It produced this :-

                                          Which I was then able to mount into a collet chuck to do the opposite side and bringing it to size.

                                          Time for the blow torch again to separate them.

                                          Dressed the bottoms to remove the solder film that had been left and had the following. smiley

                                          Nick

                                          #202822
                                          Nick_G
                                          Participant
                                            @nick_g

                                            .

                                            Question.

                                            I intend to mount the soleplate with it's bearings in situ facing upwards to drill them out close to size on the mill with the last pass being a reamer. (yes I know line boring would be better. But I don't have T slots on my lathe cross slide.)

                                            I will gradually make the holes larger with progressive drills (new nice sharp ones) before stopping slightly short of target for the reamer.

                                            My question is when drilling into the gunmetal bearings that is known for 'snatching' what sort of step between drill sizes should I go for.? Also what sort of speeds for these drills.? I am presuming a slow feed will also help avoid any snatching.

                                            Cheers, Nick

                                            #202841
                                            JasonB
                                            Moderator
                                              @jasonb

                                              I would probably go 1/4", 3/8" then reaming size slowing the speed down quite a bit after the first drill and as slow as you can get it for the reamer. Make sure you get a good accurate start into the second bearing, a long series 1/4" centre drill is handy for this sort of thing as it can be guided by the 1/4" pilot hole in teh first bearing.

                                              Yes using the mills downfeed will help a lot to stop snatching

                                              #202844
                                              GarryC
                                              Participant
                                                @garryc

                                                Hi Nick

                                                I found that a lot of heat is generated very quickly with gunmetal and it helped to try and keep things as cool as possible as the snatching seemed to 'especially want' to happen when hot, I took my time and let things cool between each drill bit – still managed to burn my finger last time though as I remember. It was something Jason said to watch out for at the time – as usual it was very good advice..

                                                Hope it goes well..

                                                Cheers

                                                Garry

                                                Edited By Garry_C on 01/09/2015 17:18:44

                                                #202851
                                                Michael Gilligan
                                                Participant
                                                  @michaelgilligan61133

                                                  Having negligble experience of these steamy devices … A question if I may:

                                                  Would it be wise [and/or common practice] to insert a thin shim between the halves before boring?

                                                  MichaelG. [happy to be ridiculed or educated]

                                                  #202852
                                                  JasonB
                                                  Moderator
                                                    @jasonb

                                                    I've never shimmed model bearings, Its done quite often on the full size hit & miss engines though with either bronze or white metal bearings. My thoughts are that we are not going to be running them lots and if they should wear then the mating "flat" areas are small enough to be rubbed on a sheet of Emery to remove a little metal if you needed to close up the hole.

                                                    I usually solder mine together before boring so you will get a slight gap once they are melted apart and the solder cleaned off.

                                                    As Nick's No 4 does not use a separate top half of the bearing and bearing cap the only way to close up any gap would be to pack up the lower bearing. I prefer to have separate caps that are clear of the bearing housing when the bearing is in place so they can close up any gap in the bearing in future.

                                                    J

                                                    #202862
                                                    Nick_G
                                                    Participant
                                                      @nick_g

                                                      .

                                                      Cheers for the replies guy's

                                                      Michael. – I understand your logic regarding the shims and I it's a fair point.

                                                      Jason and Garry. – Thanks for the information.

                                                      My plan is (please tell me if its a good one or not) is to mount the soleplate with just the bearing bottoms fitted. Then with a piece of precision ground 12mm stock in the collet holder adjust the mill bed until I can just feel contact on both bearing bottoms with a feeler guage.

                                                      Remove the 12mm stock and using the DRO I have fitted to the mill subtract the width of the feeler guage. Then subtract an additional 6mm to hopefully bring the center of the mill over the line of the bearing split. Pop on the caps and then sally forth.

                                                      Good plan or a disaster in the making.?

                                                      Cheers again, Nick

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