#MT25 

Andrew, as I said in a previous post, you need to what is called "back off the drill" this is so simple to do. Get an oilstone and give a few rubs on both the cutting edges, keeping the stone parallel to the axis of the drill, this will change the cutting angles and give it a bit of a negative rake. I feel sure you have had this type of problem with your woodturning tools, negative rake tools . You will also encounter this snatching action with Perspex and quite a lot of other plastics.

Hello again Andrew.I love your "warts and all" approach, showing what went wrong as well as what went right. So instructive for us newbies.My lathe is MT0 taper both headstock and tailstock. With very little friction, I found the chuck rotating so often that I held onto it like grim death while drilling. I now open up the chuck until the jaws are inside and give the chuck a firm tap with a brass hammer to get it seated. This seems enough to prevent rotation.Milling the top of the bearing seating to width is what I would do, given a reliable mill. I did this with a flat file to get a straight cut across both seatings concurrently but with the file off vertical, tapering into the seating. Once the top was on size, I brought the file up to vertical then used the (looks familiar) 9.5mm round file for the rest.To avoid measuring errors with the bearings, I made the crankshaft first, but I'm using 7mm silver steel. The 3rd attempt was satisfactory, using the Loctite and 1/16" pins method. I found 12mm copper plumbing pipe round the curved part of the bearing gave an almost perfect centre in the 3 jaw chuck. Having faced the ends of the brass, I concluded that cutting the brass in half and drilling the two separately, gave a better chance of holes concentric with the casting. With the same setup as facing, I turned the inside bosses to length to centralise the crankshaft. My attempt to turn a 7mm taper mandrel ended up at exactly 7mm: "wringing" wasn't going to work. So I drilled and tapped M4 down the middle, just with a taper tap, and split the shaft lengthwise with a hacksaw. A short grub screw forces the shaft open, holding the brass well enough to turn without any obstruction.Having clamped the bearings into the soleplate, with the crankshaft in situ and running smoothly, I drilled and tapped one stud hole in each bearing, bolted the bearings down and removed the clamps. Drilling, tapping and bolting down the third stud hole didn't bind the crankshaft so I thought I was on to a winner.The 7BA HSS tap snapped in he 4th hole, so goodbye tap and casting!I've bought replacement tap and casting, and today's the big day for drilling and tapping.Looking forward to the next instalment.Regards, Len

I enjoyed your video and took your idea and made a mandrill. And wot a finish it worked a treat. Thanks for that.

Andrew, thanks again for another instructive video. I would go along with Robert Oswalt's comment about drilling brass and gun metal that the point of the drill should be modified to stop it catching. I can't give you details but it is written up somewhere on the Model Engineer website blog and in various text books. Very enlightening watching you tackle the various problems and devising the solutions. Martyn

I nice clean hole is always a preference 👍

so glad you are making another engine, love your friendly low key comentary

Hi Andrew like your videos on the stuart v10 just wanted to add when creating the curve on the bottom plate for the brass bushes you could have also used a bull nose end mill that would of made life alot easier for you .

I find it strange that the bearings have a flat surface to function as the bearing cap. Maybe in the long run it makes it so that there are fewer machining tasks. I have heard that to prevent a drill from catching and screwing itself in, you can flatten the point of the drill so it more resembles an end mill. Thanks for another great video

Hi Andrew, when milling the radius for bearing seats. clamp the part to an angle plate and use the boring head, saves filing the radius by hand. ATB Adam

Trying to learn before I decide to buy the castings. When you center drilled the bearing on the mill why not just drill and ream it there? Sounds like I would need a reamer to fit the shaft size as do not have now. What about a ball end mill to cut the casting rather than file the radius?

Look on the Clickspring channel there is a video on there about changing your drill bits to drill in brass. If you don’t do what he says apparently a drill bit without the modification tends to grab.

There is a YT channel ClickSpring. A guy who does a lot of work with brass. Shows how to grind drill bits so they don't grab and how to make turning cutters for brass. Haven't done any of his mods but good food for thought. Just an FYI....

Hi Andrew, My 10v is just up to this stage. Could you please help me with a few points? When you marked out the sole plate how did you mark the circular part of the bearing? I can only think of jenny callipers because there is no centre part to work from. What type of milling cutter was that and where did you find it? I’m not sure if HSS cutters will survive for too long on cast iron, so I’m thinking it might have been carbide. I thought of aligning the sole plate on the mill by using a round metal bar laid along the crankshaft axis and then aligning the bar at right angles to the bed. My initial thought with milling for the bearing was that a 7/16” ball-end cutter might be able to finish the milling process in one final pass but I went off the idea because I could only find that type of cutter in HSS and because a final pass with such a cutter would give less margin for any fine adjustment - always assuming it didn’t do any unintentional milling! I’ve already made the dial indicator holder you showed in part 3 of this series and it works really well. In a different thread I asked you about milling vices. I’ve bought the vice you recommended and I’ve ordered the steel to make your vice clamps. Keep up the good work with your excellent videos. Cheers, Chris

you should have used a four jaw independent chuck to drill that bearing it would take ages with the three jaw chuck and shims!!

I think the bearing design was for convenience of production and not function or for ease of machining, or they would be captive bearings with caps to hold them down. Stuart overly simplified their 10V. with caps, the soleplate could be bored/drilled for a cylindrical bush, and be easier to accomplish than dealing with a weird shaped casting. I have a vintage 10V I bought at auction but if I make one myself I'll bore and ream a round bronze rod and mill a flat

I noticed you didn't line-bore the two crankshaft bearings?

i think those bearing stock are not extruded but castings too

Move over Abom79 we’ve a Yorkshire007 coming to take your spot.