MetalworkingFun Forum

Invited a new friend from one of the motorcycling forums I'm on to come over to the shop with his Frankenbike project. Neil is an "ex-pat" from the UK (Manchester area, IIRC) and is building a custom bike from several. He's got a "Smithy" 3-in-1 type machine at home, but it's too small for this part of his project.

Today he brought over the rear swinging arm from an Aprilia 250 GP bike, to be fitted to the frame of another bike. I think it's a Yamaha RZ350 frame, but I am sure that twin-cylinder two stroke motor is the one he'll be using. We had to take 4.5mm off each side of the swingarm, at the pivot points. This will allow the Aprilia part to fit between the other frame. There are NO square or straight surfaces to reference from, so we first turned a plug out of 6061 aluminium and bolted it to a plate of the same. This Ø32mm plug just fit into the bores for the needle bearings which the swingarm pivots upon. It gets the pivot axis somewhat square and perpendicular to the table, aligned with the spindle of the machine.



We used lots of clamping, including use of two of my Starrett No.190 & 191 "Little Giant" Jack Screws and one of the machinist jacks that I made as a freshman in vocational school in 1973 (and had never actually used before today.)




Here's Neil doing the flycutting on one side:


Then the other:


Neil reported that when he got back to his shop, the part "fit like factory parts". This made me happy, and well worth the 3-1/2 hours we worked together on it. He didn't have to, but he brought me a round (casting?) of some naval grade of bronze that's about 2-1/2" in diameter and about 30 inches long as "barter." I don't know when I'll have an application for such a material, but you know how we all are about "stock".

Thanks Neil!

I've asked him to join up here, though I know he's got limited time. He works for a large volume casting company out of Spain, and travels an awful lot. When home he also likes to ride motorbikes, but mostly on the track.

A nice creative set-up Ken. Parts like that can be quite a challenge to get well aligned and rigid enough to machine without an unwelcome surprise.

I once spent nearly an entire day fixturing a large weldement to a CNC mill and hardly slept a wink that night thinking about machining it the next day. It turned out well but with all the time I had invested in it, it was a nerve racking experience.

Tom

Nice job! I'm glad there is someone else who drags you into your shop and makes you play

Nicely done, some times it takes hours to set up and 20 minutes to actually do the job.

DaveH

(10-21-2013, 08:29 AM)DaveH Wrote: [ -> ]... some times it takes hours to set up and 20 minutes to actually do the job.

DaveH

That's usually my SOP.

Ed

That's just about what it was in this case too. First we discussed options such as tilting the head 90º. I dismissed that because although the head can spin 360º, I don't like to run the higher speeds with the oils in the head seeping around inside.

Nine passes of 0.5mm on each side didn't take long at all, and the part was rigid enough that I probably could have used a good face mill in one pass.

Customers that drop off a job at shops don't realize the amount of setup times to get the job done properly. Any properly run shop owner cannot spend hours on the setup and only charge for the actual machining time.

Any time I've ever asked a quote of a machine shop, it always seemed to me they put in set-up time (done by the slowest one armed machinist they had.) In fact I think one even figured in set-down time.

Having changed the curtain drops on my Beaver Partsmaster to better contain the cutting fluid, the new clean pvc drops made everything else seem dim and dingy! The polycarbonate windows were yellowed with age - not sure if they were originally amber, or if it's just oil and sunlight - certainly there were several different shades, and the bits covered by the fixings were almost clear but not entirely. I'd ordered replacement cut sheets a few weeks back and was awaiting 'the right time' which came today. I wanted to do a 'soak test' of my Traub cnc lathe to see if I'd cleared an intermittent axis drive fault, so had a couple of hours when I was just baby sitting it, so fitted the windows.

Ever so slightly better

Wow - that is quite the difference. I'd love to see some video of these machines in action.