Milling on the lathe w/out a milling attachment (rate my setup)
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Rogan Creswick
I need to cut a 0.190" wide slot, 0.300" deep in a ~1.75" wide chunk of steel, and it's a part for my milling machine, so I can't do it on the mill. I don't think the tolerances are particularly tight, but I'd like it to be as close as I can reasonably get it to the part I'm replacing. Anyway, this is the setup I'm thinking of using -- setting the height relative to the spindle with either adjustable parallels, gauge blocks, machinist screws, or some other form of shims / spacers. I'm interested in hearing other suggestions -- I may just use some HSS toolbits as guides and do it with a file (likely pre-cutting some kerfs with a bandsaw). My test cuts last night were pretty slow (0.015" DOC, top speed on the lathe, and feeding by hand at about 0.5" per minute), I don't think I can run the spindle fast enough for the 3/16" endmill I'd need to use, but maybe I can rough it out with files / saws and do the finish cuts this way. Maybe I should be doing a series of plunge cuts, though? How much longitudinal force can I put on an endmill in a 4-jaw? Here's a link to a video that may better show the setup: https://photos.app.goo.gl/grCbvUpZ27K1sVdG9 Thanks! --Rogan |
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tgerbic
It will probably take a lot of time to mill this and put quite a bit of stress on the lathe. That is a lot of material to remove. I would suggest you do some layout and either bandsaw or hacksaw away as much steel as possible, leaving a small amount to mill away with better precision. Due to the amount of curved surfaces, a lot of filing will be required.
Alternately, you may be able to cut/bolt/weld together a bunch of rough pieces of metal to make a temporary replacement and use the mill to make the actual replacement. I would probably take this route. |
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Rogan Creswick
Oh, I'm only planning on milling the little slot with this setup -- the big step I'll definitely cut out with a bandsaw, and the more intricate cutaways / curved bits are not necessary features, I think that's just material savings from the production casting. I have a surface grinder that I can use to get a precision thickness on the big step, but I can't cut a slot with it :D On Tue, Feb 28, 2023 at 4:42 PM tgerbic <tgerbic@...> wrote: It will probably take a lot of time to mill this and put quite a bit of stress on the lathe. That is a lot of material to remove. I would suggest you do some layout and either bandsaw or hacksaw away as much steel as possible, leaving a small amount to mill away with better precision. Due to the amount of curved surfaces, a lot of filing will be required. |
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tgerbic
What is the broken piece made of? If cast iron, welding might not be feasible. If steel, it could be welded up enough to reuse to make a new piece. You might be able to weld it back together but I suspect some of the welds would need to be machined, like at the right where the slot is, and this could be hard on the lathe and hard to hold in place during machining.
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tgerbic
So it is cast iron.
Have you thought about making the larger flat section, all the way across the bottom, out of a single piece of steel, perhaps cutting out the half round with a metal hole saw. Then take another block of steel and machining the part that sticks up. Then bolt/weld the two pieces together. This is probably not what you want as a final fix but it should provide a good replacement to get the mill up and running again. I don't know what bounds you have around the part but making it in two pieces might be a good option, |
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James Bishop
You could consider drilling out the bulk of the material. Either a series of holes across the width of the slot, or one or two holes in the side down the length of it. On Tue, Feb 28, 2023, 3:53 PM Rogan Creswick <creswick@...> wrote:
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Do you have an end mill holder that will fit the spindle of your lathe? If so, use that! If not you could make or buy one relatively cheaply. I've got one that has a MT3 taper, got it for my HF 7x10 mini, kept it when I sold off the mini-lathe a year or so ago, since it also fits the spindle on my Atlas TH42, and the spindle adapter for my SB Heavy 10L. You can get them from Shars, CDCO Tools, Little Machine Shop (where I got mine), and probably many other places. If you're anywhere near OKC, Steve's Wholesale Tools had two of them in the precision tool cabinet a week or so ago at the Sante Fe store. Call it $28+tax, I think. Similar to this: https://www.amazon.com/SHARS-Holder-Adapter-Drawbar-202-1225/dp/B07YLCPC76 Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement. SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better
On Tuesday, February 28, 2023 at 05:53:21 PM CST, Rogan Creswick <creswick@...> wrote:
I need to cut a 0.190" wide slot, 0.300" deep in a ~1.75" wide chunk of steel, and it's a part for my milling machine, so I can't do it on the mill.
I don't think the tolerances are particularly tight, but I'd like it to be as close as I can reasonably get it to the part I'm replacing. Anyway, this is the setup I'm thinking of using -- setting the height relative to the spindle with either adjustable parallels, gauge blocks, machinist screws, or some other form of shims / spacers. I'm interested in hearing other suggestions -- I may just use some HSS toolbits as guides and do it with a file (likely pre-cutting some kerfs with a bandsaw). My test cuts last night were pretty slow (0.015" DOC, top speed on the lathe, and feeding by hand at about 0.5" per minute), I don't think I can run the spindle fast enough for the 3/16" endmill I'd need to use, but maybe I can rough it out with files / saws and do the finish cuts this way. Maybe I should be doing a series of plunge cuts, though? How much longitudinal force can I put on an endmill in a 4-jaw? Here's a link to a video that may better show the setup: https://photos.app.goo.gl/grCbvUpZ27K1sVdG9 Thanks! --Rogan |
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That is a good idea! Remove as much material as possible, and take all the load off the end mill you can. Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement. SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better
On Tuesday, February 28, 2023 at 08:03:40 PM CST, James Bishop <bishopaj@...> wrote:
You could consider drilling out the bulk of the material. Either a series of holes across the width of the slot, or one or two holes in the side down the length of it. On Tue, Feb 28, 2023, 3:53 PM Rogan Creswick <creswick@...> wrote:
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Rogan Creswick
I don't know what the original part is made of -- maybe an aluminum casting? I think more likely some pot metal, though. It is not magnetic, so it's not cast iron / steel, and it will just crumble in your fingers. I thought this bit of scrap I'm using was cast iron, based on the chip formation, but it doesn't rust as quickly as cast iron, and I noticed a scribe mark that looks like A2 on one face, so maybe it's that. In any case, that's what I'm using -- it's a shifting shoe to move the reversing pinion into place. It'll be living it a bath of gear oil or grease (different discussion, that), and for the hours I'll put on this machine I'm sure it'll be just fine. All of my endmill holders are for the mill, they're R8 taper -- I hadn't considered getting any for the lathe, but that's an idea I'll have to consider. I'd rather not for just this job, but if I need to do more work like this that'd certainly be worth it. Most of the time I have a bridgeport clone (made by JET) at hand, so this isn't a problem :). --Rogan On Tue, Feb 28, 2023 at 6:34 PM Bill in OKC too via groups.io <wmrmeyers=yahoo.com@groups.io> wrote:
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Another thought is to use a angle grinder to rough out the shape. With a cutoff wheel & grinding wheel, you can rough it out quickly. Then finish it on the lathe or mill. Is there and way you could cob up the mill for this job? Al
From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> On Behalf Of Rogan Creswick
Sent: Tuesday, February 28, 2023 6:53 PM To: SouthBendLathe@groups.io Subject: [SouthBendLathe] Milling on the lathe w/out a milling attachment (rate my setup)
I need to cut a 0.190" wide slot, 0.300" deep in a ~1.75" wide chunk of steel, and it's a part for my milling machine, so I can't do it on the mill.
I don't think the tolerances are particularly tight, but I'd like it to be as close as I can reasonably get it to the part I'm replacing.
Anyway, this is the setup I'm thinking of using -- setting the height relative to the spindle with either adjustable parallels, gauge blocks, machinist screws, or some other form of shims / spacers.
I'm interested in hearing other suggestions -- I may just use some HSS toolbits as guides and do it with a file (likely pre-cutting some kerfs with a bandsaw). My test cuts last night were pretty slow (0.015" DOC, top speed on the lathe, and feeding by hand at about 0.5" per minute), I don't think I can run the spindle fast enough for the 3/16" endmill I'd need to use, but maybe I can rough it out with files / saws and do the finish cuts this way.
Maybe I should be doing a series of plunge cuts, though? How much longitudinal force can I put on an endmill in a 4-jaw?
Here's a link to a video that may better show the setup: https://photos.app.goo.gl/grCbvUpZ27K1sVdG9
Thanks! --Rogan |
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Rogan Creswick
I'm not good enough with an angle grinder to manage a 0.190" cut, but I can get close with my bandsaw (aside from cutting the back; I can kerf a lot of it out, then clean up with the southbend "horizontal mill", which seems like the best option at this point). I can't easily get the mill back together easily because the reason I'm taking it apart is to repair the "front" gears -- the bearings are totally shot (to the point of almost seizing up) and this part is necessary to run the *back* gears. If I really have to I can repair the bearings in the mill, so that I can use it without the back gears, but this seems like a part I should be able to make with what I do have working right now, so I thought I'd give it a shot. So far I don't think this is significantly harder than re-assembling the top half of the mill head, remounting it, tramming everything in, an then tearing it down again. --Rogan On Tue, Feb 28, 2023 at 7:03 PM ww_big_al <arknack@...> wrote:
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mike allen
Could you put a cutoff wheel in your surface grinder & work it that way ? animal On 2/28/2023 7:23 PM, Rogan Creswick
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A couple for the lathe, very common sized sf endmill, like 3/8" & 1/2", and you can tackle about anything small without having to tear down a setup on your mill. A t-slotted table and an angle plate, to make setups on the lathe easier... Working on doing that for all my lathes. Even the Unimats. ;) They can actually be set up as a milling machine, for tiny work, so I made a couple of milling tables. One is t-slotted, one has holes that will get tapped M6x1 as soon as I can get done messing with the house and cars. Everything here but the Atlas lathe, a large and small drill press, and the air compressor, are awaiting at least a bit of restoration work. There's an Atlas MF horizontal mill that needs the switch installed so I can see what else it needs, an HF mini-mill that was working when the guy sold it to me, but needed at least some adjustments, and there's a Lewis Shaper, and a Craftsman bandsaw that just need motors installed. Everything else needs from more to a lot more work. The Heavy 10L is most in need of work, as it spent five years in a very leaky barn. I got maybe a third of the way into getting the rust off the attachments and saddle, compound and such, and then got stopped cold for quite a while. I could have the two Unimats running in a week or so. Got all the parts, bearings and belts needed, but I'm trying to convert them to run off 24vdc motors. Everything is here, and just needs assembled. Don't even have deskspace enough to do them. This next couple of weeks I'm going to work on cars and the shop. Shop first, as much as possible, though my wife's wheelchair lift crapped out this afternoon as we were about to leave for her PT appointment. I had to pull it out of the van to get us there. Realized today that it's bee sitting nearly 20 years. I've found lube in several of the machine tools that was nearly or way past becoming varnish. May be able to ressurect the gear motors, or may have to replace them. Hope to find out tomorrow. Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement. SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better
On Tuesday, February 28, 2023 at 08:44:15 PM CST, Rogan Creswick <creswick@...> wrote:
I don't know what the original part is made of -- maybe an aluminum casting? I think more likely some pot metal, though. It is not magnetic, so it's not cast iron / steel, and it will just crumble in your fingers. I thought this bit of scrap I'm using was cast iron, based on the chip formation, but it doesn't rust as quickly as cast iron, and I noticed a scribe mark that looks like A2 on one face, so maybe it's that. In any case, that's what I'm using -- it's a shifting shoe to move the reversing pinion into place. It'll be living it a bath of gear oil or grease (different discussion, that), and for the hours I'll put on this machine I'm sure it'll be just fine. All of my endmill holders are for the mill, they're R8 taper -- I hadn't considered getting any for the lathe, but that's an idea I'll have to consider. I'd rather not for just this job, but if I need to do more work like this that'd certainly be worth it. Most of the time I have a bridgeport clone (made by JET) at hand, so this isn't a problem :). --Rogan On Tue, Feb 28, 2023 at 6:34 PM Bill in OKC too via groups.io <wmrmeyers=yahoo.com@groups.io> wrote:
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Rogan Creswick
That's a good idea. I don't have an arbor for any wheels I have, but something I should figure out some day. I'm trying to get ahold of the folks at MLA tools to buy a T-slot table, but haven't had any luck so far (not that I can finish that project without a mill, just planning ahead somewhat -- although I mostly want it so I can mount a DRO on the cross slide). --Rogan
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Is this the sort of arbor you'd need? See photo attached. I'm thinking that enough spacers would let you mount a cutoff wheel on something like this... I WANT a surface grinder, but haven't found one I could afford in all the years I've been hunting machine tools. I have this arbor, and maybe a 2nd one like it, and a box of 4 or 5 pink wheels about 1/2" thick that my school threw away a while back. I pretty much cleaned out the dumpster. ;) I don't have any use for them, and they are part of the clutter I need to dispose of somehow. I could make you a very good deal on them if you're interested. And even if they won't help you with this particular problem, you'd be welcome to take them for small change or trade, if they'd be of use to you. The label under the arbor is from one of the wheels in the box. I apparently didn't get any photos of the grinding wheels themselves. Think I had a couple of loose wheels, too, and I'm probably keeping at least one. Guy Lautard has a bit on an improvised and hand-fed surface grinder in one of the Bedside Readers. It would be entirely sufficient to my needs. Speaking of Lautard, if you pdf's of any of his books that I don't have, you could trade them. I've been looking for a copy of "Hey, Tim, I Gotta Tell Ya..." for years. I'm looking for copies, not original books. Those are too valuable for this stuff. I've got pdf's of his Bedside Readers, the Radius generation book, and comprehensive index. I bought paper copies of the revise Machinist's Bedside Reader and Strike While the Iron is Hot. They are currently missing in action. Hoping they wound up in a box, and not left at one of our doctor's appointments. William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement. SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better
On Tuesday, February 28, 2023 at 11:46:49 PM CST, Rogan Creswick <creswick@...> wrote:
That's a good idea. I don't have an arbor for any wheels I have, but something I should figure out some day. I'm trying to get ahold of the folks at MLA tools to buy a T-slot table, but haven't had any luck so far (not that I can finish that project without a mill, just planning ahead somewhat -- although I mostly want it so I can mount a DRO on the cross slide). --Rogan
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