triton
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Post by triton on Jan 23, 2022 19:03:08 GMT
I am getting to the point in my loco build to start machining the wheels. Having finally retired and started to get back on the "machining bike" after 40 something years, its taking a little practice again and I am a little rusty on machining cast iron.
Need some feedback experience on cutting tool type, speed of lathe for a 7" diameter wheel.
Also wanted advice on best wheel cutting procedure:
1. Face off inside of wheel (Backside)
2. Drill center hole for wheel shaft and ream.
3. Turn wheel around and face off front of wheel to correct width.
4. Mount wheel on a stub shaft and machine to correct diameter and wheel profile.
After reading numerous books, magazines and YouTube videos, any additional advice or things to look out for or avoid would be appreciated.
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uuu
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Post by uuu on Jan 23, 2022 19:29:40 GMT
What you really want is for the front side of the wheel to look good as it revolves. It's entirely possible that, in the casting, the front and back don't quite line up. So machining anything on the back first seems wrong to me.
I like to put the raw wheel in a four jaw, front side out, and adjust it until it "looks best" when rotating. This might be the inside of the rim (always a difficult bit), or some other prominent feature. Then you can turn the outside round and face off the rim, not necessarily to a final run. But this means that everything else that you do will preserve this "looks best" result.
Wilf
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stevep
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Post by stevep on Jan 23, 2022 19:36:01 GMT
LBSC always used to say, in his 'words and music' that you should chuck the wheel backwards but with the rim of the front running true. This is hard to achieve, because you can't see the front of the rim. So my preferred method is to chuck the wheel front outwards, and get the rim running true. Take a light skim (face and tread), and then drill through with a small drill (1/8"). Reverse the wheel in the chuck, and get the hole running true. Then you can start turning/drilling/boring safe in the knowledge that the rim is running true.
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samc88
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Post by samc88 on Jan 23, 2022 23:55:48 GMT
Turn the wheel profiles to rough dimension first and then using a mandrel in the lathe you can take them all to the finished dimension without having to move the crossslide, means you get all 4 to the same size.
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triton
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Post by triton on Feb 1, 2022 2:58:13 GMT
Thanks for all the help. Much appreciated.
Stevep: Facing the front of the wheel first to get the rim running true makes much better sense than doing the back first. Excellent advice.
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triton
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Post by triton on Feb 3, 2022 19:37:32 GMT
Just a question: If you face off the front and outside rim and then drill a 1/8" center hole per Stevep, why wouldn't you go ahead and drill and ream the 3/4" shaft hole at the same time BEFORE reversing the wheel and facing the inside??
Reverse the wheel (front facing the lathe chuck) mounting the wheel on the mandrel, turn the rough tread diameter and then finish of the wheel profile?
Am I barking up the wrong tree??
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triton
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Post by triton on May 22, 2023 18:23:02 GMT
Had to take a leave of absence from loco building due to health issues, but back on it again.
After reading more machining books, watching more videos, and the help above (Really liked the reply above from stevep), I developed a plan of action list to start wheel machining.
Can the wheel machining experts offer comments or suggestions to see if I'm going about this the right way so that I don't end up with a pile of scrap metal or a loco that wont go in the right direction?
My procedure:
1. Put rough wheel casting in 4-jaw chuck facing toward tailstock. (Grip on outer rim) 2. Put indicator on face and tread to get running square and round. 3. Machine face of casting. 4. Machine center hub to required dimension width and depth. 5. Machine tread to diameter. 6. Center drill casting and then drill 1/8” hole through. 7. Repeat for all four castings.
8. Turn casting around in 4-jaw chuck. (Outside machined face facing away from tailstock) 9. Grip on machined tread, flat against chuck jaws. 10. Install a dead center to wheel and a live center in tailstock. 11. Put dial indicator on the dead center (closest to wheel) and adjust 4-jaw chuck to center wheel. 12. Remove indicator, dead and live centers. 13. Machine face and center hub to dimensions. 14. Machine rim flat to outside dimensions. 15. Open up the center hole with drill. 16. Bore center hole to dimensions.
Question: Bore or ream center hole? (Wheel will be Loctited to shaft)
17. Remove wheel from chuck. Repeat for other 3 wheels.
18. Change to 3-jaw chuck and make a mandrel to suit shaft diameter. (Do not remove from chuck) 19. Mount wheel on to mandrel spindle. 20. Machine the 2-degree tread slope. 21. Machine the outer rim profile to dimensions. 22. Repeat for the other three wheels.
Everybody's help and comments are greatly appreciated - Thankyou.
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Post by steamer5 on May 22, 2023 21:53:20 GMT
Hi Triton, About the only thing I can see I’d do differently is to have the inside of the tread running true, well as true as you can get it. Pretty sure it’s been mentioned on here several times, the inside & outside of the rim may not be concentric as cast & by having the outside running true the inside well appear to wobble once machined. By truing on the inside & then machining the outside they should be.
Cheers Kerrin
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SteveW
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Post by SteveW on May 23, 2023 8:40:09 GMT
Interesting subject and I've been pondering the same/similar issues but with a couple of cast flywheels for my hit n'miss kit.
The bit giving me sleepless nights is the slight miss-alignment of the two sides of the castings. With a flywheel the bulk of the metal is in the rims while the hub is relatively sparse. If I get it right for one face it'll be slightly off for the reverse face so some sort of compromise needs building in to the chucking procedure.
Of course the spokes need to run true as do the hubs. The current thought being to find and spot the centres on each side, setup between centres and then clock the faces looking to replicate any wobble in the chuck before the first skim to true.
Its likely that I'm over thinking it all and any error is in the range of three fifths of F all but perhaps multiplied by the speed of revolution and compounded by all faces being visible to the wittering classes.
Edit: having run my colours up the flagpole and recovered to the inner sanctum for further contemplation ...
I have to consider the flywheel faces as true to the spokes so really only need to worry about any slight offset of the two halves of the casting. The wobble, using schoolboy trigonometry, can be used the determine any sheer offset between the front and rear faces and the difference/average used to optimise when setting in the four jaw.
Comments welcomed.
(872)
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Post by RGR 60130 on May 23, 2023 10:03:55 GMT
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uuu
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Post by uuu on May 23, 2023 10:24:32 GMT
Hi, Triton. Some comments on your proposal.
You can't always rely on drills running true. So on your bore or ream question, you can ream if you like, but only after you've bored the hole, so it will be be true. The advantage of reaming is that you can get all your wheels to exactly the same size, and this will make the turning of the axles easier.
I like your mandrel idea - and this also will be easier if the bores in all the wheels are exactly the same.
Step 5 - you might like to leave this a bit over-size at this point.
I'm not so fond of your drilling 1/8" and then using this to find the centre afterwards. If the drill wanders off a bit, given that it's the other side you'll be using as your reference, it won't be quite right. You could bore and ream your hole at this stage, and use your double centre idea - or (maybe better) a finger-dial indicator in the bore to set up the other way. If you want to stick with the drilling method, a nice new drill may wander less.
Good luck
Wilf
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stevep
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Post by stevep on May 23, 2023 11:22:36 GMT
The reason for my process is to ensure the tread and hole are concentric. Drilling a small hole when the front is running true may wander a bit, but this is relatively unimportant compared to the tread not being concentric with the hole in the wheel.
After reversing the wheel to face the back, and drill/ream/bore the hole, the back of the wheel and the hole will be accurate with respect to each other. The wheel can then be mounted on a faceplate with a mandrel projecting out of the headstock taper, enabling the tread to be machined concentric with the hole. By using the indexes, you also make sure they are all the same size.
A note of caution - Martin Evans used to suggest a mandrel to fit the headstock taper with a thread to hold the wheel to the faceplate! Obviously, if you tighten a nut on the thread, you will just pull the taper out of the headstock. Better to bolt the wheel to the faceplate with separate fixings.
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Post by chris vine on May 23, 2023 13:42:44 GMT
One thought: Your mandrel idea is a good one, however I think that the wheel will vibrate and chatter badly when you try to machine the outside tread etc.
A better idea is to use the faceplate with a plug mandrel which fits in the headstock taper. (I have a blank with sleeves which fit over it for different size bores in jobs.). Then you can fit a peg in the faceplate to drive on a spoke and you can use the tailstock with a live centre and a little pusher piece to hold the wheel against the faceplate.
The faceplate will much reduce any tendency to chatter.
The other advantage of working like this is that, once you have a back face machined, and a bore, you can swap the wheels round very easily. So you can do just tiny operations on each one and use the dials etc to help you make them all the same. Swapping wheels in sequence only takes seconds - wind back tailstock, slip in next wheel, use tailstock to hold to faceplate. Ditto Repeato as someone famous said!
Hope that helps. Chris.
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triton
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Post by triton on May 28, 2023 23:02:41 GMT
Wow: Thanks for all the excellent input. The holes for the main driving shaft is 3/4". So if I drill the 1/8" hole on the front wheel face side, turn over the wheel and drill a slightly larger hole (Even if its a little off center), then bore the hole to the correct diameter, everything should then run true......I hope!
Stevep - Could I make a mandrel in the 3-jaw chuck and mount the wheel on it and then machine the rim. (I cant make heavy cuts on my machine anyway!). Do this with all four wheels without removing the mandrel. Just a thought!
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triton
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Post by triton on May 28, 2023 23:19:33 GMT
RGR 60130 - Your photos of "Blue Peter" were of great help. Thanks also for the help.
PS. I was born in Seaham Co. Durham. Beautiful city - Durham!
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Post by brvoelker on May 29, 2023 10:59:44 GMT
the second to last set of Wheels I did were for a 3-1/2" Netta (about half your 7" diameter). Some comments (not a sequence of Operations): 1. I measured the distance between the Tread and Inner Rim diameters with a Dial Caliper at various points around the Wheel. The measurements were so close, first Op was grip on the Tread and finish turn the Backside, turn Flange OD parallel to finish size, and bore & ream the Axle Hole. 2. The Tread length was less than the depth of the Chuck Jaws. In order to grip the Wheel using the front cast Face as a datum, I used double-sided Scotch Tape to stick 1/8" Shims to the relevant face Surfaces of the Jaws to pack the Wheel out for clearance to turn the Flange OD. 3. I used a machined-in-place Fixture ~2" OD Stock, held in 3-Jaw, machined to 7/16" dia with a true Face to hold the Wheels. The end of the 7/16" Stub was threaded 3/8" NF for a Nut & Thick Washer. 4. as Chris mentioned above, with a Fixture like this it is easy to set up to do one Operation, say "finish turn Tread", and do all Wheels (in my case qty 8) one after the other. 5. I have a 1" stroke Dial Indicator which I can clamp anywhere on my Lathe Bed. That makes jobs like facing the wheels to finish thickness so easy. I use it continuously. 6. with the Netta Wheel Castings I could not finish turn the face of the Counterweights - their inner Radius was less than the outer radius of the Crankpin Boss. The counterweights had to be milled. 7. I took the ~2" diameter Fixture discussed above and drilled & counterbored 2 Holes in it. I bolted it to the Mill and used it to locate the Wheels to put in the Crank Pin Holes. After setting it up, centering the Mill, moving the Y axis to the Throw, I used a piece of Stock same diameter as the Crank Pin Boss in the Drill Chuck to set the wheel angularly.
the last set of Wheels I did were for a 7-1/2" Mogul (8" diameter). Some comments: a. these were done on an industrial Lathe using steel Soft Jaws. All Operations were done in the Soft Jaws. b. like #1 above, the Measurements indicated it was OK to start machining locating off the cast Tread. c. the cast-in Counterweights did foul the soft Jaws and the Jaws had to be relieved to clear them. d. the Wheels did sing during some cuts requiring adjustment to the speeds & feeds.
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stevep
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Post by stevep on May 29, 2023 12:53:06 GMT
Wow: Thanks for all the excellent input. The holes for the main driving shaft is 3/4". So if I drill the 1/8" hole on the front wheel face side, turn over the wheel and drill a slightly larger hole (Even if its a little off center), then bore the hole to the correct diameter, everything should then run true......I hope! Stevep - Could I make a mandrel in the 3-jaw chuck and mount the wheel on it and then machine the rim. (I cant make heavy cuts on my machine anyway!). Do this with all four wheels without removing the mandrel. Just a thought! I would be a bit sceptical about this working. You would be relying on the grip on the axle hole (presumably with a locking nut) to transmit the force to counteract that from the turning tool on the tread/rim. I always use a form tool to turn the tread and root radius, and even in bottom back gear, this tends to chatter. On a mandrel held in the 3-jaw, I would think it would be impossible. The advantage of using the faceplate is that the wheel is held securely, and at a guaranteed right angle to the axis of the lathe. A mandrel (left in place between wheels) ensures concentricity and repeatability.
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triton
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Post by triton on May 29, 2023 20:28:18 GMT
Thanks - Good advice from both last 2 posts. I will follow your procedure(s).
I have not got to the form tool part yet! I need a 5/64" radius at the tread to rim and a 3/64" radius at the rim tip.
Any recommendations for buying/making a form tool for the tread and rim??
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Post by ettingtonliam on May 30, 2023 8:03:16 GMT
I made a form tool for 'Locomotion's wheels using the age old method of repurposing a stout flat file. I ground it smooth on both sides near the end, heated it to red and let it cool in the embers on the hearth, and once soft marked out the profile of the tread and flange, and cut to shape. Once that was done, I hardened it again, and tempered to light straw. Polish all over and it was good to go. A very low speed, and it lasted well for the 4 wheels.
You must mount the wheels on a solid backing block though, with a central locating spigot.
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Post by brucevoelkerding on May 31, 2023 12:17:51 GMT
I have to imagine using a Form Tool is prone to chatter on a light Lathe. You might get away with it if your Wheel can be bolted to the Faceplate. I am in the Chris Vine Camp - do each Tread Operation separately.
I cannot use the "traditional" Shank in the Headstock plus Faceplate as a previous Owner of my Lathe absolutely destroyed the Morse Taper by running a Boring Bar into it multiple times. Thus, I turn a Stub Mandrel with a true Face in the 3-Jaw. I was able to complete all the Mandrel Operations on my Netta Wheels (qty 8) in one Day (no more than 8 hours and that included the finish Turning of the Mandrel). I was taught never to leave a Part chucked in a Lathe overnight - that is how I am sure I was able to do them all in one Day.
The fronts of the Wheel Bosses were faced using the 3-Jaw (I checked with a Dial Indicator that the Jaws ran true in the facing direction).
Using a HSS Tool ground with the correct Nose Radius per the Wheel Standard and set up so it can both turn & face - 1. face front of Wheel 2. rough turn Tread & face Flange 3. set Topslide over and finish turn Tread OD - after turning "paint" the Corner Radius with Sharpie for Step 4 4. set Topslide over, reposition Turning Tool, and finish face Flange - the Sharpie allows you to see the blended cut in the Radius root 5. flip Wheel around and taper face back of Flange (this is an IBLS Standard in the States) 6. change to a Chamfer Tool & chamfer Tread to Front Face Edge 7. chamfer Flange OD to Flange Front Face 8. chamfer Flange OD to Flange Back Face 9. with Wheel held Wheel Back out, blend Flange OD and Flange Chamfers into a Radius with a File. 10. at this Point the Wheels looked so nice (Reeves castings), I used a very narrow (~.03") Grooving Tool to turn a Recess at the Wheel Rim ID to clean up 11. I had enough Time left over to grind up a pointed Tool and put a Groove in the Wheel Face to indicate a dummy Tire Joint.
To be clear, each of these Operations were completed on all the Wheels before doing the next Operation. Yes, this does mean I reloaded the Wheels approximayely 7 * 11 =77 times (Hex Nut OFF, Hex Nut ON). Note between Operations you usually do not have to remove the Wheel - when Wheel 8 Operation 1 is finished it becomes Wheel 1 Operation 2 (therefore 7 instead of 8 changes). It helps to have a Cad profile of the Wheel Tread so the Chamfers in Steps 7 & 8 can be calculated. I have a well worn (early 1960's era) South Bend Lathe, but the Cross Slide is repeatable. That in conjunction with a Way mounted Dial Indicator to measure Carriage Position is all I used. When finish turning the Treads with the Top Slide, I nipped up one of the Cross Slide Gib Screws to lock the Cross Slied and I locked the Carriage.
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