PDA

View Full Version : Modifying a Wohlhaupter UPA4.



LexD
7th Jun 2017, 07:50 PM
The first picture shows the MT shank being sliced off as it did not fit my machine.
There was a lot of work done to achieve the result shown in the second picture where the modifications to the actual head are almost complete. Now I am working on a couple of interchangeable shanks.

368208

368209

jhovel
8th Jun 2017, 10:57 PM
That would have hurt.... even I'm cringing :)

LexD
10th Jun 2017, 11:13 PM
This is the Differential Screw which is made from a 20 x 2.5mm socket head set screw. The small end has been screwcut to 16 x 1.5mm as per Wohlhaupter dimensions giving a 1.0mm differential.

368292

Picko
11th Jun 2017, 05:07 PM
A couple of days ago I had to google Differential Screw because I had never heard of it and now it pops up again. Nice work by the way.

LexD
11th Jun 2017, 10:53 PM
Thanks Picko, I have always wanted to have a reason to use a differential screw thread in a project and this was it, although it is not my design, I am just following the original Wohlhauper drawings.

This is what the genuine detachable shank type head looks like.

368305

Anorak Bob
13th Jun 2017, 11:18 AM
Nice work Techo.:2tsup:

Any chance that you might have taken a few photos of the work between the lopping off of the arbor and the head ready for its new arbor? I remember looking very keenly at UPA3s when hunting for a boring / facing head and most featured an integral arbor not readily accommodated in my mill's 30 taper spindle. At the time amputation seemed a bit risky. Your results prove otherwise.

Bob.

LexD
13th Jun 2017, 01:36 PM
Yes Bob, I do have some more photos of the various processes although nothing very exciting and the quality is not that good but I will post them later.

Here is the drawing for the UPA3.


368317

LexD
14th Jun 2017, 10:38 PM
A few photos of the work in progress -

Drilling and reaming the dowel pin holes on vertical mill.
368331


Screwcutting the 16 x 1.5mm thread.
368332

368333


Screwcutting the differential screw on a small CNC lathe. These screws are quite hard at around 45Rc.
368334


Grinding the hardened silver steel dowel pins on a mandrel. I'm not sure how the Wohlhauper dowels are done but on these ones I have a 4mm reamed hole right through. To remove the dowels from the boring head the 4mm hole is filled with grease and a 4mm dowel pin is driven in "hydraulicing" the pin out of the hole.
368335

Anorak Bob
15th Jun 2017, 12:57 AM
Thank you for the progress photos Techo.

I'm wondering, would your little blue CNC lathe just happen to be a Hercus Compulathe?

Bob.

LexD
15th Jun 2017, 02:03 PM
It is a Compulathe Bob.

LexD
23rd Jul 2017, 11:02 PM
The modifications are now finished after relocating a 5mm hole, through the side of the 60mm diameter journal, for a spring and pressure pad. The original hole could not be used because the hole for the differential screw broke through into it making it unusable in it's present position.

The last photo shows the head fully assembled and waiting for a new shank to be finished.


368900

368901

kwijibo99
24th Jul 2017, 10:19 PM
Beautiful work Techo.
That's certainly the most ambitious and well executed UPA shank conversion I seen done.
Looks as good as a bought one.
Cheers,
Greg.

LexD
25th Jul 2017, 08:10 PM
Thanks Greg, and thanks for the Wohlhaupter information you provided a couple of months ago.

LexD
4th Aug 2017, 10:50 PM
I finally got around to starting on the new shanks for the Wohlhaupter, the first one is an MT4, I will also make an NT40. I had one 1200mm length left, of 90mm diameter EN36A, of two that I purchased from a scrap metal dealer about 20 years ago. After about 45 minutes of roughing it out I had the basic shape shown in the pictures.

369065

369066


https://youtu.be/iDZhRrxvie4

LexD
12th Aug 2017, 10:54 AM
First cut on a 6.8kg lump of EN36A for the NT40 shank.

369157

After roughing out the shank it now weighs just over 2kg's.

369158

Anorak Bob
12th Aug 2017, 08:41 PM
It looks the part Techo. :2tsup:

How will you hold the 40 arbor while machining the Wohl mount?

Bob.

LexD
13th Aug 2017, 10:46 AM
Bob, after the internal 16mm drawbar thread is cut I will pull the shank back against it's 65mm diameter flat face on a faceplate. Holding the shanks for grinding after hardening will be another story.

Anorak Bob
13th Aug 2017, 11:53 AM
Bob, after the internal 16mm drawbar thread is cut I will pull the shank back against it's 65mm diameter flat face on a faceplate. Holding the shanks for grinding after hardening will be another story.

The advantage of having a largish lathe!

LexD
24th Aug 2017, 10:20 PM
A little more progress on the shanks, this is the setup I used to bore, drill and screw cut to ensure that the threaded hole stays concentric and straight.

369587

LexD
11th Sep 2017, 07:41 PM
The 2 shanks are ready for Carburizing, hopefully later this week.

369925

LexD
19th Sep 2017, 05:19 PM
Pack Carburizing at 910 degrees C today.


370156

LexD
20th Sep 2017, 10:35 PM
They are now ready for Hardening and Tempering. I filled the threaded holes with Refractory Cement (Fire Clay) to prevent extra carbon being absorbed by the threads which could make them very brittle.


370162

.RC.
21st Sep 2017, 10:34 AM
You did quench them after pulling them from the furnace?

LexD
21st Sep 2017, 07:32 PM
You did quench them after pulling them from the furnace?

No, I didn't, they were allowed to cool overnight while still in the box. Today I reheated them to 860 degrees and quenched in oil to refine the core, tomorrow I will reheat to around 800 degrees and quench to refine the case. They will then be tempered.

LexD
22nd Sep 2017, 07:37 PM
Grinding the #4MT shank.
370175

Various stages of completion.
370176

Anorak Bob
22nd Sep 2017, 08:26 PM
Very nice Techo!

How are you supporting the tailstock end of the arbors, a dummy centre screwed into the drawbar thread or the tailstock's centre running off a chamfer at the entrance to the bore? I like the hose clamp "dog". One to remember.

Bob.

LexD
22nd Sep 2017, 10:02 PM
Yes Bob,it's running between dead centres on the 60 degree chamfers machined in each end.

LexD
3rd Oct 2017, 10:32 PM
370405

370407

I was having second thoughts about the scrap yard material I used for the two Wohlhaupter shanks/arbors considering I have had it for over 20 years and the colour coding on the end of the bar is almost completely worn off.
A bit late I know, but I decided to have it tested to confirm that it was actually EN36A, the scan results are below.

370406

It came up as 9310, the AISI equivalent of EN36A so all is well. It appears that the XRF does not have European standards in its data base.

KBs PensNmore
4th Oct 2017, 12:25 AM
Unfortunately your attachment 370405 comes up with "Invalid Attachment specified. If you followed a valid link, please notify the administrator (http://metalworkforums.com/sendmessage.php)"
Nice piece of workmanship on your shank/arbor. Thanks for the WIP report.
That's an amazing interesting piece of equipment, as you say Every Home machinist should have one of these.
I'll bet it wasn't cheap, or is it a work perk??
Kryn

Oldneweng
4th Oct 2017, 11:25 AM
A quick check shows prices from $8k to $22k for secondhand on US EBay. Would be handy to know of someone with such a machine. Steel merchant or similar. Could I just check this trailer load of scrap mystery metal?:D

Dean

.RC.
4th Oct 2017, 01:38 PM
Only thing is those machines do not check carbon content, and they emit X-rays and I believe have a limited life.

LexD
5th Oct 2017, 02:55 PM
Yes Kryn, that one cost one of our major scrap recyclers around $40K, as compared to the previous one they used to use which cost 4 or 5 times more and was limited in what it could do.

A better scan showing an exact match, it was a bit hard holding the gun steady on the tapered circular arbor while it took reading.

370425

LexD
5th Oct 2017, 09:55 PM
I finished the last bit of grinding today, touching up the mating faces and grinding the internal locating diameters to 60mm.

370433

LexD
15th Oct 2017, 10:20 PM
This is the set up I used to drill the 10mm pin holes using a Tungsten Carbide end mill to achieve the final diameter. The holes are 40mm between centres.

370618

Anorak Bob
16th Oct 2017, 09:34 AM
Crisp as usual Techo.:2tsup:

How did you grind the recessed face of the arbor? A stone with a recessed centre on an internal spindle?

Bob.

LexD
16th Oct 2017, 06:56 PM
Yes Bob, that's exactly how I did it.

370626

Anorak Bob
16th Oct 2017, 08:49 PM
Now you have me curious Techo as to how the arbor is mounted to the workhead. Is the brown spacer hollow and both the arbor and spacer held in position by a drawbar? (The problem with such a scenario is that you probably ground the face of the spacer prior to mounting the arbor so something a bit trickier must be going on.)

Bob.

LexD
17th Oct 2017, 09:53 PM
You are correct again Bob, the arbor is pulled back against the fixture with a 16mm drawbar made from allthread which inturn pulls the fixture against the flat face of the workhead spindle. The home made eye nut and pin were used to hold the fixture for grinding the ends.



370676

Anorak Bob
17th Oct 2017, 11:00 PM
Fantastic stuff Techo. I'm storing all these tricks away for that rainy day!

LexD
20th Oct 2017, 10:33 PM
Thanks Bob, on a side note, did you end up making the Over/Under attachment for your Hommel Werke Height Micrometer. (http://metalworkforums.com/f65/t140510-todays-tools-gloat/latest/post1847337#post1847337)

Lex.

Anorak Bob
21st Oct 2017, 02:22 PM
It's still on the list Lex.

I'm a bit daunted by the spring clip. Any suggestions as to how to make it given that Hommel probably would have used a press to achieve its curved form?

Bob.

LexD
23rd Oct 2017, 10:33 PM
It would be a bit awkward to make Bob. I guess you could try making one from annealed spring steel and then heat treating it.

LexD
9th Dec 2017, 08:12 AM
A short video showing how the shanks are installed and removed.


https://www.youtube.com/watch?v=3vju1HWbdrI&sns=em