# CMT Ursus 250 Repair: 3) Carriage Hand Wheel



## RobinHood (Aug 27, 2021)

The hand wheel on the carriage was broken. I tried really hard to repair it, but without success. The material is White Cast Iron. It is considered non-weldable, non-brazeable because of its chemical composition (high chromium content). CMT uses this material extensively on hand wheels and dials as you can highly polish the surface or media blast it to give a nice soft satin finish. It also grinds very well - dial bearing surfaces are all cylindrically ground the lathe.

The wheel is in one piece now, but the aluminum bronze weld did not bond with the WCI as the surface does not wet. The reason it is staying together is because of the weld prep. There is no structural strength whatsoever.

Front view of wheel





And the back side





I don’t have any ductile iron stock big enough (8+” diameter), but I did find some 4330 of suitable size. Here the Carolina saw is slicing a 3+” wide disc off the log. I had it set for the slowest speed and light down feed. Took 90 min to get through. Neither the blade nor the log got appreciably warm - exactly what I wanted. This stuff can work harden pretty easily.

The 8.5” x 3.25” disc weighed just over 52 lbs. I’ll weigh the wheel once it is done.






Here we are roughing out the front.





And done. The OE is beside the billet for comparison. I am leaving the contouring of the hand portion to the end. I like to have flat faces for easier mounting to the rotary table to cut the two spokes. The sharpie marks roughly show what needs to be removed off the rim and what stays on the front.





And here is the back roughed out on the lathe. The OE center hub was cylindrically ground inside to fit on the shaft as well as the outside to accept the travel dial. I will probably use the tool post grinder to finish off these surfaces - not 100% certain yet, as 4330 turns really nice with carbide tooling. I may just go with turned surfaces.





More to come…


----------



## RobinHood (Sep 14, 2021)

I did not grind the ID and OD with the TPG. Fine tuned speeds and feeds a bit more to get even better surface finishes and just turned the OD journal and the ID bore. Here it Is on the apron for a first fit-up.





Next I mounted the wheel to the 12” BP rotary table to start working on the two spokes. Started with the 4 “corners”. The radius of the OE’s spokes - to - circumference is just over 24mm. The location of the Center of the circle was determined by using geometry. I set the Y-offset on the mill table and the angle on the RT. As mentioned elsewhere, this RT can accurately divide the circle into degrees, minutes and seconds. Since the bulk of the inside of the hand wheel was removed on the lathe, I had to use an center cutting end mill to locate the corner circle because of the step (You can see it in the picture). Plunged a 1/2” carbide EM through first, followed by a 3/4” one. Then switched to the boring head to open the hole to dimension.





After milling the excess off the inside circumference and “stitch drilling” the roughed out wheel spokes look like this. I had previously machined the counter balance weight (6 o’clock position on the wheel) and drilled & tapped the handle mounting hole (12 o’clock position)






There is still a little extra material to come off the inside to blend into the corner rounds. In the picture above you can see that they don’t quite match yet.

The OE wheel has a circular cross section of the perimeter surface - both inside and out. The outside I can turn on the lathe with a form tool.

The inside is another story. It can’t be turned on the lathe because of the counterweight and the handle boss. I think I am going to move the RT onto the Deckel KF2 3D pantograph and see if I can do some contour milling using a ball nose end mill.

Stay tuned for that…


----------



## YYCHM (Sep 14, 2021)

Could you not use a corner rounding endmill and the RT to do the interior rounding?

Corner Rounding End Mills - Results Page 1 :: KBC Tools & Machinery


----------



## RobinHood (Sep 14, 2021)

Yes, that is an option.

I have to check, but I don’t think I have one big enough. IIRC, the largest one in my stash is 1/2”. The nominal diameter is 26mm. Plus, I only have imperial corner rounding end mills.


----------



## RobinHood (Oct 6, 2021)

I did not use the KF2 for the next steps.

I did find a suitable round-over end mill to machine the inside surface. I also used a ball nose end mill to blend in the transitions from the circumference to the spokes.





Center finding on the handle bore to set up the axis of rotation to mill the boss.













All the blending done











That left the spokes themselves. Using a template on the KF2 would have been the best (and precise) option. Would have to make one and the mill is not fully operational at this time (needs all sliding surfaces inspected and spindle bearings repacked).

So I just scribed two lines and carefully milled to the lines. Some filing and the spokes are done.










Next will be a 6mm key way through the bore and rounding over the outer circumference. I could leave the outer contour as is, but it would not match the OE hand wheel.


----------



## PeterT (Oct 6, 2021)

That's one good looking handle! All those machining steps to complete many interrelated features. Kind of illustrates why casting is used so much on machine components - where 80% of effort goes into the master pattern & at leaves machining to a lower number of critical surfaces & features.


----------



## RobinHood (Oct 6, 2021)

My thoughts exactly wrt casting vs machining from billet.

Plus all the wasted metal. So far I machined off almost 40 lbs of perfectly good 4330 tool steel!


----------



## John Conroy (Oct 7, 2021)

That is a work of art. Nice work!


----------



## 6.5 Fan (Oct 7, 2021)

Indeed a work of art. Excellent write up and pics to explain what your doing.


----------



## Dabbler (Oct 7, 2021)

As usual, perfect work!  every time you use it you can be proud.


----------



## Brent H (Oct 7, 2021)

@RobinHood : a wheel of fortune!!! That is a beauty!!  Nice work!


----------



## RobinHood (Oct 7, 2021)

Thanks for the compliments. Much appreciated.

The lathe is made to very high standards - so it deserves a decent replacement.


----------



## historicalarms (Oct 8, 2021)

Outstanding job man, thoroughly enjoyed the thread....but all the time reading through it I could hear my old mans " practical farmer voice" in the back of my mind..."I woulda fixed that in the time it took to cut through that log" and he probably would have said.
     First he probably would have went out to some old retired piece of machinery out back and found either a chain gear or pully with the same bore as the handle. drilled a hole for the crank handle and slid er' on.
    If not finding a suitable repurpose piece, his next move would have undoubtedly been to torch cut a suitably sized piece of flat 1/4" or 3/8 plate into a circle, run the rough edges over the bench grinder a couple passes, now torch cut a center piece out to accommodate the original hub, drill a hole on outer edge for crank handle...now drill through existing hub and just cut plate and bolt securely to each other...and slide er' on.

     its amazing to me, two different philosophies that end up with exactly the same outcome....a working piece.


----------



## kevin.decelles (Oct 8, 2021)

I thought about how badly I would have butchered a piece of 4xxx steel, and how my cheap tooling would have broke or squealed it’s way through the job

I appreciate the skill, equipment and tooling! 

Much to learn, far to go, and looking forward to the journey 


Sent from my iPhone using Tapatalk


----------



## RobinHood (Oct 8, 2021)

historicalarms said:


> Outstanding job man, thoroughly enjoyed the thread....but all the time reading through it I could hear my old mans " practical farmer voice" in the back of my mind..."I woulda fixed that in the time it took to cut through that log" and he probably would have said.



Thanks.

I did think like your dad at first, but only for a short while. Was going to burn out a ring from plate, weld in spokes & a hub. It would have been totally functional and the repair would have taken a whole lot less time.

But, as I mentioned above, this lathe is built to a very high standard/quality and it just would not have been right. To give you an example: the treading dial has the bore, the shaft and the mating flange cylindrically ground & bronze bushed! Everything on this machine is built like that. I am absolutely amazed at the quality and effort that went into it. You could not pay for this kind of thing today.

Here are some pictures of the threading dial:


























Yes, it needs a bit of TLC (one gear tooth mangled a bit - I will make a new one), but even just after a cleaning, the dial runs buttery smooth.

That is my main reason to spend so much time and effort on refurbishing this lathe. (Plus I like challenges…)


----------



## RobinHood (Oct 8, 2021)

kevin.decelles said:


> I thought about how badly I would have butchered a piece of 4xxx steel, and how my cheap tooling would have broke or squealed it’s way through the job



I think I was lucky that the 4330 machined as well as it did with the tooling I have. I have learned a lot machining all sorts of SS for other projects and those experiences were directly transferable.

I have spent hours on this hand wheel, not just with set-ups, but also tinkering with speeds and feeds, DoC, and trying different inserts to get the finishes you see.


----------



## PeterT (Oct 8, 2021)

Yes, you can see the quality in those parts. Look forward to the gear making


----------



## YotaBota (Oct 9, 2021)

Beautiful work RH.
Do you have a melting pot to put the chips back together for the next project?
All I need is another 50 years experience and 7 tons of chips and I might get to this level. lol


----------



## RobinHood (Oct 10, 2021)

Unfortunately no foundry capability. It would be nice…


----------



## RobinHood (Oct 16, 2021)

Little more progress over the last couple of days…

Used a 1/2” corner rounding end mill as a stationary tool on the lathe to contour the OD of the circumference of the hand wheel. Careful manipulation of X & Z feed allowed me to nibble away the material. As we approached the 1/2” radius, it became increasingly more difficult to prevent chatter as an ever longer portion of the arced cutting edge started engaging. 72 rpm and light infeed followed by tool retraction as the harmonics changed seemed about the sweet spot.

Here you can see the end mill and the workpiece’s matching radius.





Since the corner rounding end mill was not rotating (as it normally would in a milling operation), the surface finish was an exact replica of the radius grind of the end mill’s one cutting edge. It was quite good, but nowhere near where I wanted it to be. (This is a reasonably high quality Butterfield CREM).

You can see the dull finish and the tooling marks here.





Next was to polish the surface to eliminate the tooling marks - did that with progressive finer sand paper.





And old vs new.





Need to make a tool to cut the 6mm key way as I don’t have any metric broaches. That will then complete the hand wheel.


----------



## Tom O (Oct 16, 2021)

Beautifully done


----------



## RobinHood (Oct 23, 2021)

To broach the 6mm key way, I needed to make a single lip broaching tool. I found a suitable 1/4” piece of HSS and a 1/2” boring bar that I could then hold in a collet in the mill.

Since there was not enough room on the Clarkson T&CG for both a vise and the spindexer, I mounted everything on the mag chuck of the Ingar surface grinder.





The profile I was after looks something like this.









Set-up on the mill.





Turns out that this cutting edge geometry was too aggressive and required a lot of force to push through the 4330 steel bore. The tool kept digging in - when it did cut. Lots of tool deflection as well. I also lost the cutting edge about 1.5mm into the 3mm depth.

So back to the surface grinder to change the geometry. I basically went for a scraper style edge this time around, as seen here.




That worked much, much better. The cutting forces were greatly reduced with 1thou DoC. Also, the cut was totally controllable and no digging in of the tool. The cutting edge stayed very sharp to the end.
You can see the huge difference in the chips produced. Left is the negative rake edge chips, on the right are the scraper style edge chips.





Had to step-over 0.23mm on each side to get the key way width to just a shade over 6mm as the tool was intentionally ground to < 6mm wide.

All done & installed.









The final weight of the hand wheel is 8 lbs 4.5 oz. That is over 40 lbs of 4330 chips to whittle this thing out from a solid disc. Casting is definitely the way to go if you are making more than one…


----------



## PeterT (Oct 23, 2021)

Very nice work. End result looks right at home on the machine. Keyways look so harmless from across the room, but there appears to be a lot of factors to get right for clean accurate  results. So you opened up the slot to full width by alternating left & right a bit to the 'line' with each progressive depth stroke?


----------



## YYCHM (Oct 23, 2021)

Was that keyway cut using the manual quill down feed on your mill?


----------



## RobinHood (Oct 23, 2021)

The cutter ended up 5.57 mm wide after I cut in all the relief angles (it started out as 1/4” = 6.35mm). The key way needed to be 3mm deep (1/2 of the 6mm width). I cut the key way 5.57mm wide to 3mm deep on the center line. That removed most of the material. Then I moved off center  0.23mm and cut the one side all the way down to the 3mm depth. Step over 0.23mm to the other side of center and clean up that side. Total width 6.03mm. Close sliding fit for a 6mm key.

Yes, all this was done on the mill using the manual quill down feed handle as a way to move the boring bar (with the broaching bit) up and down in the bore. The wheel was conveniently held in the vise using a V-block against the fixed jaw. The x / y axis of the table were then used to position the bore correctly under the quill. DoC (in-feed) was controlled with the y-axis. The broaching operation worked very well once the cutter geometry was correct for the material I was cutting.


----------



## historicalarms (Oct 24, 2021)

One-off Broach cutters can be made quite easily using HSS cutters of the desired size. Cut a piece of bar the same size as your bore that you desire to key. now mill a groove lengthways in the insert that corresponds with key cutter, now you have a guide same as any manufactured broach set.
    Grind one side of the HSS cutter to a slight angle and notch some teeth into it with a dremmel ( how many you want is up to you, I used 3). Now you can cut a small amount out of your bore with every pass by shimming the back of the cutter. 
    I have used both hyd press & arbor press....arbor requires more effort but hyd takes longer to retract & reset for each pass. 

     The use of a backing insert makes cutter angle a lot mot forgiving....no "deflection problems". Although hogging out a keyway is a lot less demanding, precision Barrel rifling cutters have experimented with cutting angles for decades and every one I know claims the thing that has to be right first is the cutter holder has to fit the bore exact to counter any tool deflection. If the boreriding tool holder is perfect, the cutting angle is a lot more forgiving ( one of the most respected cut rifling  barrel makers in NA, I have watched him grind a cutter by hand & eyesight).


----------



## RobinHood (Oct 24, 2021)

@historicalarms , I do agree with your points on home made broaches and the fact that a “backed” tool will deflect less (or not at all) when used in a broaching operation.

I don’t have an arbour press. I do have a little bench top hyd press. I have successfully used the hyd press with my DuMont SAE broaches. I have even used the broaches in the lathe applying pressure using the tail stock. It all works.

I have broached using a shaper - which I no longer own.

And I have used the mill spindle with a single lip cutter - like in this case.

It basically came down to what would give the highest probability for success without going out to buy a commercial 6mm broach (I would have to make a custom bushI. and backer pins regardless, as the bore is overly long and a non-standard diameter). Keeping all this in mind, I decided on the single lip broaching tool held in a 1/2” boring bar using the mill spindle as a ram. Except for the faulty cutting edge geometry initially, I was pretty confident that it would work well. And it did, after the cutter was corrected.

I had a lot of time invested in this part and really did not want to screw it up during the last operation. So I fell back on a procedure I am very familiar with and know that works. Plus, I had all the components of the tool on hand (other than it needed the cutting edge ground) to complete the job.

I always like to hear about other methods of doing operations - makes me think and evaluate what I could do differently next time. So thank you.


----------



## Janger (Oct 24, 2021)

Nice job and write up Rudy. I wonder what a metal 3D print for this part would cost? Not as fun or interesting but still. The US navy was looking for a way to rapidly characterize the measurements of hand wheels on ships - valves and such - to enable quick replacement. It’s a similar problem - they also need one custom hand wheel at a time. I’ll see if I can find that link.

US Navy Challenge: Rapid Design Tool for Advanced Manufacturing


----------



## Janger (Oct 24, 2021)

Rudy I was re-reading your discussion of trying to weld/braze the old wheel. It got me thinking about TIG welding CI - I did a little research and it seems people claim it's possible with a nickel filler rod. Welding CI Not that I've tried this myself. Do you do any TIG welding?


----------



## PeterT (Oct 24, 2021)

My guess is outsourced 3DP metal would be insanely expensive because it's mostly a function of mass (more material cost, more print time, more structure stuff, more baking, more post-finishing...). 
A while back I was interested to just get a ballpark $/cc type cost metric. Even that was not straightforward. If anyone has seen a chart like that I'd be interested. I can see vendors not wanting to commit online without firs seeing a CAD file because of so many potential variables. But still...

Have you ever submitted something for a (metal) quote, Janger? I've always been tempted to upload one of my model engine parts just for the heck of it. I'll do it on a dare LOL








						How are prices calculated?
					

By uploading your 3D model through the model upload page, you'll get an instant quote for your 3D printed product in various materials. Our system will quickly analyze your model and show you the p...




					support.shapeways.com


----------



## RobinHood (Oct 24, 2021)

John, thanks for the links. Interesting that the Navy has similar problems with one-off wheels for valves.

Yes, I did try to TIG weld it. As a matter of fact I tacked the individual pieces together with just the heat of the tungsten. That held well enough for the wheel to be in one piece and that is when I took most of my measurement. When I then tried to finish weld the cracks, i discovered that the CI was not really wetting - when I did get a puddle, the material just flowed away, ie it was too hot and the CI had reached its melting point. The “no puddle” problem steered me towards using Aluminum-Bronze as a filler (mainly because of the lower melting point). Unfortunately it did not stick, as, again, I could see any wetting action.

I then tried welding using O/A - same problem: by the time I got a puddle, the CI was just flowing away. Also no wetting action.

I have not tried hi nickel rods. It was suggested by other members here. Now that I have a new, functioning wheel, I will most likely try it. What do I have to lose?

I am pretty sure that the material is White Cast Iron — most folks consider it non-weldable, as I have learned. The article in your link draws the same conclusion.

Metal 3D printing would most likely work. I don’t have CAD software to design the part so that I could  even send out a file to a printer to get a quote. I think prices have come down, but I suspect it would still be quite pricey.


----------



## Dabbler (Oct 24, 2021)

I don't know a way to braze white cast iron, but reading this article helped me to understand the differences:






						ГИДРА САЙТ НАСТОЯЩИЙ | HYDRA ССЫЛКА ONION : КУПИТЬ КОКАИН | ЗАКЛАДКИ САЙТ ОНЛАЙН
					

На дворе осень, а это значит пора закупаться на ГИДРЕ! Скрась скучное осенее настроение покупками на сайте hydra. Рабочая ссылка сайта гидра у нас на форуме! Просто кликай на ссылку и попадешь на него...



					topwelders.com


----------



## Tom O (Oct 25, 2021)

Nice article thanks


----------

