First Lathe Project

[ddkhalaji]

Hi Guys,

So after setting up, then taking down, reinforcing my work bench, and re-setting my lathe. Here's my little beast, I'm pretty happy with my Proxxon PD400. It was the best lathe that I could afford at the time (which is now haha  ).



I've attempted to start my first lathe project, which is a mini surface gauge from the book titled Lathework a Complete Course by Harold Hall. The gauge is made from mild steel, before I had the book I did a few practice cuts in delrin.

Anyways, I had to cut the 38mm mild steel rod by hand, I'm not going to lie, it was a mentally painful. I lost my patience a few times and rushed it.



Yep, the rushing definitely made it wonky 



Okay, so I loaded up my material in the chuck, jaws were reversed so I squared it up as detailed in the booked to ensure it turned as concentric as possible. I center drilled it successfully and had then held the work safely between chuck and dead center.

I started to face the end of my work. I am using the HSS tools I bought with the lathe from Proxxon. I noticed that facing left a lot of little V-grooved rings, and it wasn't smooth to touch. I had the lathe running at 330 rpm.

I set it to 660rpm and tried again, same thing, just with a little smoke off the work. As I was taking more passes, I kind of feed it too much in, as the end is cut a little wonky one end really stuck into the cutter and stopped the lathe.

After I inspected the cutter, there were these chips in the end. You may notice a small radius on the edge, I did that after on an oilstone trying to get the chips out of the cutter. After 30mins on honing, it was already past midnight so I went to bed.




My question is, are the grooves left in the material from facing because the tool went to a very sharp corner? After I get the chips out of the cutter, and have a small radius on the corner, would it face a smoother? I will post up pictures of what the material looks like in a few hours, as I don't have them with me right now.

[lordedmond]

first question what is the steel you are using

you should be using  EN1A  cuts like butter

by the look of your comments you have some GGQ ( Good General Quality ) which the rouge dealer sell as EN1A 

if you can get EN1Apb  then get that its a leads steel and as you will not be welding it it will be OK and very easy to machine on a lathe of your size

Stuart

[Meldonmech]

Hi,
    When sawing, try to use the whole length of the saw blade. From the looks of your blade you are only using  60%, so the effort and  sawing time are 40% more. When sawing let the top half of your body do the work, swing from your hips keeping your elbow firmly against your waist. These sawing principles will make your sawing much quicker and easier.
                    When setting your lathe tool against a chuck jaw for squareness, add another couple of degrees to angle your tool to the left. Start facing your  bar from the center, using a light cut, and a constant fine feed. This should give you a good finish with your rounded tool.
                                                Good Luck   David
                                                                                                                                                                                             
                                                                                                                                                                                                                                                       

[Anzaniste]

Hi,
    When sawing, try to use the whole length of the saw blade. From the looks of your blade you are only using  60%, so the effort and  sawing time are 40% more. When sawing let the top half of your body do the work, swing from your hips keeping your elbow firmly against your waist. These sawing principles will make your sawing much quicker and easier.
                    When setting your lathe tool against a chuck jaw for squareness, add another couple of degrees to angle your tool to the left. Start facing your  bar from the center, using a light cut, and a constant fine feed. This should give you a good finish with your rounded tool.
                                                Good Luck   David
                                                                                                                                                                                             
                                                                                                                                                                                                                                                     

I would add to the sawing advice ; - Don't go at it like a rabbit on the job and don't press down too much. Nice steady full length strokes aiming more to keep it straight rather than to "get through". Don't be impatient and take a rest if you need to.

[mattinker]

 You paid for all of the teeth on the blade! Use them. As said above go slowly, it will actually cut quicker!

Regards, Matthew

[ddkhalaji]

Thank you for all your responses! I've had a lot of success tonight!

Stuart it is EN1A mild steel, I wish I could say it was (GGQ), but it was me and my cutter in the end.

David, Anzaniste and Matthew, thanks for sawing advice, I will definitely take it on board next time I'm cutting through some rod.

David, that is how I was doing the facing, as it explained it in the book..I think I may have chipped the cutter early on, and produced very bad results after that..

Here is a before shot..



After I finished tool and gave a small radius..its smooth to touch

[Jonny]

Never seen an HSS cutter like that before and the source of the problem. Its got no relief apart from top edge you have to grind them up which will only last a few times. Surprised it didn't leave chaff marks even on a robust machine.
Have a look on how to grind a tool up.

Purely as a means of seeing whether it cuts better swing round the tool about 10 degrees right and power feed backwards towards tail stock.

[Meldonmech]

Hi,
       Glad to see you are now getting the smooth finish on your facing. Help is always available on this forum, which has a vast communal knowledge waiting to be passed on.
                                                                                 Cheers David

[vtsteam]

I agree with all the comments so far about hacksawing. I also wonder about why all that paint was missing on the blade for one cut -- unless it was a used blade. If so, try a new sharp one, and for thick stock like that, a relatively coarse tooth. Bimetal blades are nice, too. Spent several years hacksawing before I got a bandsaw. Make sure you have as much tension as you can physically manage on the blade.

Now, I hesitate to say this since no one else has and maybe some feel there is a reason not to, but I often sawed round stock in the the lathe while it was turning. You should move the blade back and forth so it doesn't wear the teeth in one spot while doing this, like slow motion sawing, and not apply much pressure. And not all the way through, of course, so you don't have work leaving the lathe, but to within about 1/4" of center. Then I turned the motor off and sawed the rest of the way by hand. Speed should be slow, naturally.

Parting off is also good, but learning how to saw seems primary.

[krv3000]

hi and you is off to a good start well i have cut 100mm bar by hand noproblem 

[ddkhalaji]

Never seen an HSS cutter like that before and the source of the problem. Its got no relief apart from top edge you have to grind them up which will only last a few times. Surprised it didn't leave chaff marks even on a robust machine.
Have a look on how to grind a tool up.

Purely as a means of seeing whether it cuts better swing round the tool about 10 degrees right and power feed backwards towards tail stock.

Hi Jonny, I think the angles of the photos I took of the cutter don't do it justice. It does have front and side clearance. I do plan on grinding my own tools, I have been reading how to run a lathe by south bend, which explains how to grind and the angles of the different tools, and for the different metals.. I'm waiting for blanks to arrive, and buying a bench grinder.

Do you or anyone else have advice for buying a bench grinder?

Hi,
       Glad to see you are now getting the smooth finish on your facing. Help is always available on this forum, which has a vast communal knowledge waiting to be passed on.
                                                                                 Cheers David

 Thank you!

I agree with all the comments so far about hacksawing. I also wonder about why all that paint was missing on the blade for one cut -- unless it was a used blade. If so, try a new sharp one, and for thick stock like that, a relatively coarse tooth. Bimetal blades are nice, too. Spent several years hacksawing before I got a bandsaw. Make sure you have as much tension as you can physically manage on the blade.

Now, I hesitate to say this since no one else has and maybe some feel there is a reason not to, but I often sawed round stock in the the lathe while it was turning. You should move the blade back and forth so it doesn't wear the teeth in one spot while doing this, like slow motion sawing, and not apply much pressure. And not all the way through, of course, so you don't have work leaving the lathe, but to within about 1/4" of center. Then I turned the motor off and sawed the rest of the way by hand. Speed should be slow, naturally.

Parting off is also good, but learning how to saw seems primary.

Hi VtSteam, yes it was an old blade, it is also a 32 TPI blade as I'm usually cutting thin stock. I was hesitant to saw in the lathe, maybe in later in down the track when I build my confidence I will give it try, thanks for the pointers. I agree with you in learning to saw seem primary. Thank you.

hi and you is off to a good start well i have cut 100mm bar by hand noproblem 

Hi, thanks    100mm  I better just suck it up then..

[AdeV]

Do you or anyone else have advice for buying a bench grinder?

Buy the most powerful one you can afford. I made the mistake of buying a cheapo one (£20 from B&Q IIRC), as soon as you touched the wheels with a piece of metal it literally ground (haha) to a halt.

I'm lucky enough to have 3-phase, so when I landed on an old 3-phase machine, I snapped it up. Cost less than the B&Q heap, and has loads of torque. It also spins on for maybe 10 mins after being turned off, so the bearings are pretty good too...