Scott vacuum engine (flame gulper)

[uuu]

You'll need a slowish spindle speed.  And the wide cut will show up if your head is out of alignment!

Wilf

[Sanjay F]

Thanks all - I know exactly what you mean as I had to remove 0.050" to get the surface flat; it was twisted in every possible direction!

My arm feels like it going to fall off after the number of passes back 'n' forth I've had to do; however, it was a new cutter and although it looks stripey its fantatsically smooth, so worth it 

I've seen these indexable face mills which look like they'll do the job, but not found one with a 3/8" Whitworth drawbar which is strange

[Sanjay F]

You'll need a slowish spindle speed.  And the wide cut will show up if your head is out of alignment!

Wilf

How slow is slow?

[vtsteam]

With an HSS tool it's pretty much the same thing as how fast you'd run a lathe with a part of the same diameter as the cutter makes in your fly-cutter. If you don't have one put up a chart on the wall of speeds for different diameters vs materials. This will work more or less for either.

In other words, assuming an HSS tool in each, if you were turning a 2" dia blank in the lathe, you'd be in the ballpark if you ran the same RPM on the mill for a 2" wide cut with the flycutter. Use a chart, not experiment with the flycutter. You can get away with more on the lathe than a stick of metal spinning around in the cutter. Don't extend the cutter very far, also. That's why you have 3 sizes.

[vtsteam]

Here's a chart I use, copied from my old Atlas lathe manual. This is for HSS only, not carbide. I added a few additional metals to the top heading, as described in the same manual. It's just ballpark and old fashioned, the metal terms are approximate, and the exact speeds are numbered to correspond to the available Atlas lathe speeds. But I find it a handy starting point for both turning and milling -- again HSS only. I have one each posted on the walls near my lathe and my mill.

[Jasonb]

Not only do you need to run at a moderate speed but as the cutting edge only comes round once per rev you need to advancethe work quite slowly too.

On the larger flycutter it is possible to use an indecable lathe tool rather than HSS so you could recon on upping the spindle speed by three times which also allows the feed rate to be increase by the same amount.

Where the face mills score is that having 5 or 6 inserts you can not only run a lot faster spindle speeds due to the carbide but also feed a lot faster. For non ferrouus you will find it hard to turn the handwhel fast enough to get the possible 400mm/min feed that they allow with a 6 insert cutter going at 2000rpm. But winding as fast as you can will do.

As most of these insert face and shell mill heads have a metric 22 or 28mm bore they also tend to have  ametric M12 thread in the arbor. So making a new drawbar may be needed for older machines with 3/8" whit

Compare the feed rates in these two videos and I'm running the flycutter at a high rpm for HSS even on the second cut.

<a href="https://www.youtube.com/watch?v=mipbeyKOIj4" target="_blank">http://www.youtube.com/watch?v=mipbeyKOIj4</a>

<a href="https://www.youtube.com/watch?v=rUo0cWFt6Tc" target="_blank">http://www.youtube.com/watch?v=rUo0cWFt6Tc</a>

[Sanjay F]

Thanks Vtsteam and Jason

I'll definitely be trying this out on some scrap so I can the feel of how fly cutters behave/misbehave!

[Sanjay F]

I'd like to say thanks to the gentleman whose build I'm following, it's great, but he isn't contactable?

The effort to make the holding plate/jig is so worth it, you can measure from the edges of it, take the everything on/off the vice and return it to position easily. If you are thinking of making one of these I highly recommend making the jig.

Today I measured up the section where the hopper will sit which is also the main datum for the vertical measurements. This casting really is all over the place and describing as banana shaped would be an insult to bananas! 

[PaulR]

This casting really is all over the place and describing as banana shaped would be an insult to bananas! 

Crikey even a cursory glance reveals that. Have you thought about making it into a boat instead? 

[Sanjay F]

Well if I can't get it to run, we'll agree to call it a boat! 

Today the casting was flipped into a vertical position on its jig. I accidently bought a extra long spot drill about 6 months ago and thought I'd never use it, boy was it useful today to spot the second upright through the first. I had to invest in a longer 9/64" drill bit and luckily bought it a few weeks ago in preparation (unusual for me  )

I then ran out of vertical height on my mill to drill the flywheel bearing and used a collet instead of a chuck to hold the incrementally increasing drill bits; I'm not sure if this is the right thing to do, or why I hadn't thought of doing that before, but I went cautiously and it worked. I then swapped that out and nibbled away at the hole with the boring head until the bearing snuggly pushes in

[Jasonb]

Collet is fine for holding the drill and usually shorter than a keyless chuck, MT or R8 collets can be used if you are really stuck.

Alternative would have been to mount the casting the other way up so the hole was closer to the mill table 

[Sanjay F]

Alternative would have been to mount the casting the other way up so the hole was closer to the mill table 

Doh   

[PaulR]

Ah, ball bearing bearings! How are they held in place and the shaft secured?

[Sanjay F]

They are loctited in place and not sure how the shaft is secured, but I found this picture of a completed one; flywheel one end and there looks be the crank and valve operating cam locked onto it?

[PaulR]