Machining a Cast Iron back plate

[Dingo Dog]

Hi Blokes

At long last I have managed to buy a D1-5 backplate from H&F to suit my lathe. The dia of the backplate is 250mm, I need to machine it down to 200mm to fit a new 4 jaw chuck. My lathe has 9 speeds, which speed would I need to use to do this, already had a bit of a go, damn stuff is a shocker to work with. Speeds on the lathe are as follows 60, 95, 145, 225, 335, 535, 835, 1320, 2000.

All my tipped tools are neutral, would I need a negative rake tool to do this job.

Regards

DD

[Bryan]

What did they slug you for that? I need D1-5 too, and it's hard to find.
Speed chart attached. Edit: To see it properly, click the thumbnail below, then when it opens click it again. You should then be able to zoom in.
PS: It only goes up to 100mm dia, but just halve that speed for 200mm, or divide by 2.5 for 250mm.

232913

[Graziano]

I bought a couple if D1-5's from an Ebay seller in South Australia. I haven't seen any lately, I think he still has them but gave up listing them.
They are cnc machined steel though and soft, like free machining steel. Will go look and find out his name again, they sold for $39.95 plus freight.

Edit: It was Ozmestore ozmestore1 items - Get great deals on Machine Tool Accessories, Metal Cutting Tools items on eBay Stores! (http://stores.ebay.com.au/ozmestore1?_trksid=p4340.l2563)

[Bryan]

Yikes, that's cheaper than I could find. Thanks Mark I'll chase him up.

[Graziano]

While I remember, He combines purchased items into the one box but does not combine freight charges, this was only a problem when I bought a 10" 4 jaw and a dial indicator at the same time.:crash::gaah:

[toolman49]

G'Day DD,
When I fitted my 6 1/2" 3 jaw chuck to an 8" backplate I left the extra material as I find it a convenient hand hold for turning the chuck by hand, and yes turning cast iron is a bitch, an old towel over the bed and a high power button magnet under the tool holder makes the clean up much easier.
Regards,
Martin

[nearnexus]

Yeah cast iron is real messy.

The dust is also carcenagenic so wear a dust mask.

It's not very abrasive so it's not as bad as grinder dust, but certainly is a bastard to clean up.

Rob

[Dingo Dog]

Thanks Toolman, neat idea with the magnet, have a few of them rare earth ones. Thought about leaving the meat on the backplate, cant though, the over size gets in the way off the guard, which I have removed to machine down to size. I like all the safety bits on the lathe.

Thanks Bryan for the speed chart, will do as you advised in regards to halving the speed for the area being machined.

DD

[pipeclay]

Use your lowest speed or your next up,have your feed set at no more than the nose radious of your tool.
If there is a scale get under it in one pass.

[nearnexus]

Use your lowest speed or your next up,have your feed set at no more than the nose radious of your tool.
If there is a scale get under it in one pass.

It's interesting that most people say machine cast at a slow speed, and yes it does a good job, but I've machined quite a bit of cast iron, and even at 200 RPM (for a 50 - 100 mm OD pulley) it's no problem.

I always cut it dry, as the book says, but speed wise I can't see any difference in results.

It cuts like butter and apart from the black mess, is pretty easy stuff to work from my experience.

Rob

[pipeclay]

Does the book ever talk about using coolant.

[nearnexus]

You can use coolant for some jobs (eg, facing), but most articles and machinists say to cut it dry on a bench lathe.

Cast iron has a high graphite content, which is the main reason you cut it dry.

The other metal you machine dry is brass. I hate machining that stuff - the fine splinters are bad news, so damn easy to get them in your skin and hard to find them to remove.

I find the best way to clean up after machining cast iron is a good vacuum and them wipe everything down with toilet paper. The paper fibers catch/pick up the particles extremely well, and then you just toss the lot in the bin.

Rob

[Clubman7]

The dust is also carcenagenic so wear a dust mask.

Rob
Nothing I found says it's carcinogenic. Still, enough of it isn't good for your lungs.

[nearnexus]

Nothing I found says it's carcinogenic. Still, enough of it isn't good for your lungs.

Looks like your right. I was told by a machinist that it was a cancer hazard, but it appears not to be a carcogen.

This sheet lists it medical risk factor.

http://www.lethiron.com/downloads/pdf/MSDS-%20043%20ABRASION%20RESISTANT%20CAST%20IRON.pdf

Still, better safe than sorry.

I usually wear a dust mask with it as it certainly gets up your nose without one.

Rob

[toolman49]

Yep, big black boogers

[nearnexus]

Yep, big black boogers

+1 on the boogers.

Rob