Stuart Twin Victoria (Princess Royal) Mill Engine

[bernard towers]

On bernard towers Said:

The hole that i mentioned is for the end of the tip that is not in use, the end facing away from the work.

Ah I see. I thought you meant it was a hole for the tip as a whole, rather than a hole for just one of the tips of the tip!

(I think that sentence goes some way towards explaining my confusion!)

Thanks.

[Dr_GMJNParticipant @dr_gmjn]

Overall I think one one thing I might do is cut the grooves staight after turning the rim flat across. That way I can offset from the centreline joint (as per the instructions – which worked pretty well for me during the trial run), and then if there’s a discrepancy at the end of the process, I can face off from each side of the wheel to make the end grooves equal distances in. I already know I have to do this to some extent, so it seems to make sense to do it last rather than first, to reduce my options to correct.

Going back to the tool holder – I have an R/T so I could possibly use that in conjunction with my 1mm milling cutter to make it?

Not withstanding Jason’s comments about stiffness – I wonder If I could make it out of round bar, with a flat milled on the end, to fit in a hole drilled in a much bigger bit of square stock?

Still doesn’t get me a 1mm wide groove tool, but at least it’s something.

[Dr_GMJNParticipant @dr_gmjn]

Can’t edit posts now, but Jason you mentioned cutting a holder using half of 55 degrees. You also mentioned using a VCGT insert which seems to be 35 degrees (closer to the 40 degrees of the grooves in the instructions)?

I don’t have any VCGT inserts, but could get a few off Amazon for this job.

I suppose the 55 degree DCGT inserts are the ones I’ve got, and would presumably require a shallower cut to make the trough/peak distances correct, which might be advantageous in terms of reducing the chance of chatter?

Thanks.

 

 

[JasonBModerator @jasonb]

Yes the half of 55deg was based on the DCGT inserts that you have, the VC would be closer to the drawing. Either way you don’t want too small a tip radius.

Round bar would do either in a block or with a flat machined on the bottom so it can be clamped down.

Do you have a rest for that belt sander? If not the other grinder will do, even if the wheel is in need of truing up you have that little sliding guide which makes the state of the wheel less of a problem as you can slid ethe cutter back side to side and it will just get ground by the high spots rather than feeding into the wheel which will replicate any undulations from the wheel.

The initial slots would be better in the lathe than the R/T a 1mm dia cutter combined with likely backlash in the R/T at 7″ diameter is a snapped tool waiting to happen. The 1.5mm x 6mm parting blades are easy to come by and cheap, it would not be hard to grind 0.5mm off one side for a short distance.

Your same round or square bar could be used if you milled a 6mm wid ex 1.25mm deep slot in the end and used 2 or 3 cap head screws to pull the blade into the slot. A sort of poor mans version of some of teh internal insert grooving tools you see.

[Dr_GMJNParticipant @dr_gmjn]

Thanks Jason. Re. The R/T – I meant to use it for making the DCGT tool holder pocket, with the 1mm cutter, not for making the rope grooves in the flywheel.

[JasonBModerator @jasonb]

Not much point in risking a 1mm cutter when a 3mm will do. Just have a runout hole as Bernard suggests or run the cut beyond the internal corner. Infact as you only want a small amount protruding the opposite point may well hang over the edge of your bar so no need to give clearance.

yes R/T would work for setting the angles as well as just clamping the vice at an angle.

[JasonBModerator @jasonb]

Bit of 12mm bar, red lines are the two initial cuts with a 3mm dia cutter having the right one longer gives the tip clearance

But grinding your own should not be too hard or need anything too fancy in the way of grinders of rests.

Take a bit of HSS either bought in or an old cutter and make a simple holder from some square bar so you keep your gingers away from the grinder, don’y have to hold the HSS as it gets hot and to also hold the cutter at a constant angle. Grind a bit of the top down to approx half thickness this can be done freehand on the grinder with uneven wheel

Set the belt sanders rest to tilt down about 10 degrees and then mark two lines at 20deg. with your square holder lined up to one mark by eye grind one side to just short of half way

Do the same for the other line to form the other sid eof your Vee tool

Should look something like this, check the angle and adjust at this stage

Freehand the nose radius by swinging the tool between the two lines with very light contact on the belt

Now to see if it works. this was a bit of 60mm cast iron and the cut 3/32″ deep without the parting gut.

First half of the video I was one handed so had to feed in until it could hear it starting to resonate then moving teh cross slide back and forth a few thou then in a bit more with the cross  slide. When the camera angle changes I am working both at the same time with a slow infeed and moving the topslide one way and then the other and it goes in quite quickly.

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