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lakeside53
03-04-2015, 10:21 PM
At the peak of "I want to have everything" I got a screaming deal on a B&S clone TB01 dividing head (CL) about 10 years ago. Well... like a lot of acquisitions from that period, I just got around to needing it.

It was "like new. The prior owner said he got it "years ago" (probably late '80) and only used it once; that's once more than I've used it. lol. I want to cut about 15 gears for my lathes, so now's the time to dust it off.

Hmmm... feels a really stiff. Worse, it of ratchets a bit at points in the rotation, particularly when changing direction. I figure its got swarf or casting sand caught in the dried out pig fat used for grease. That was a correct assumption, but not the cause and there was far more wrong.

Here's the DH after I repaired it - doesn't look a lot different to how it was before it started work on it. I didn't intend this to be more than a quick clean/lube, so no pics of the disassembly. Pretty well made - tapered roller ( 32009 Nachi) at the spindle top, thrust bearing at the spindle tail, spindle all ground and nicely finished. Overall fit and finish was good. Hey, this should be a breeze.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2194%20Custom_zpskvi8vfkr.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2194%20Custom_zpskvi8vfkr.jpg.html)

Yep.. it was full of grit inside (teaspoon or more non-magnetic sand), but none of it looked like it came though the roller bearing (from grinding wheels etc). The internal casting was sealed with paint where they could get to it easily with a brush. I suspect the grit came from the 10% they didn't paint. Strike 1. The original B&S design was basically good. No idea if it's an original flaw, but the top roller has an open gap (about a 1/16th) at the top and bad crap can get in where it can damage the roller bearing, Rollers have no ability to easily move junk out of the way. But in this case, after washing out, the roller and cup were like new. Later I'll put a 75mm (id) oil seal around the spindle flange to seal it.

The spindle bearing cup and holder:

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2181%20Custom_zpslw8aowe9.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2181%20Custom_zpslw8aowe9.jpg.html)

The ratchet feeling wasn't the grit or hard grease (awful grease had dried rock hard); it was a cracked bearing disc on the rear thrust bearing. Every time the roller dropped into the crack it felt "odd".

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2162crop%20Custom_zpsj4ooqcyd.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2162crop%20Custom_zpsj4ooqcyd.jpg.html)

But wait.. How can the roller drop into crack if the plate is pressing on a solid machine surface...? uh oh.... it's not solid. Frigg... the casting was machined to the correct depth, but an occlusion still existed: (47mm plate, 51mm diameter hole):

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2170crop%20Custom_zpsuacvqfqj.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2170crop%20Custom_zpsuacvqfqj.jpg.html)

But... the occlusion still doesn't fully explain why the plate cracked.

lakeside53
03-04-2015, 10:22 PM
The thrust bearing and tapered bearing are pulled together (preloaded) by a threaded collar on the rear of the spindle.. To lock the preload, the collar is split on one side and a screw compresses the thread.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2179crop%20Custom_zpsu7ezshhr.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2179crop%20Custom_zpsu7ezshhr.jpg.html)

Ha... the damn screw is too long. and when tightened even carefully puts a high point load directly on the bearing. This load was at 6 o'clock in the casting picture above - worst possible place. You can see the shiny spot on the screw end. It protruded about 50 thou... and I could see the contact point right on the bearing plate crack. Basically it was "locking" by driving a screw into the top bearing plate, not by compressing the threads.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2178crop%20Custom_zpseoeufzqm.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2178crop%20Custom_zpseoeufzqm.jpg.html)

Ok, mystery solved. I might have got away just shortening the screw and leaving the casting alone, but I wouldn't be able to sleep. Mounted the casting in the BP and machined down until the occlusion was gone, about 80 thou... Easier with cnc to just use an end mill, but I could have used a rotary table or boring head.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2172%20Custom_zpsuxwsfd8v.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2172%20Custom_zpsuxwsfd8v.jpg.html)

Much better :

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2174%20Custom_zpsw8apqkxi.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2174%20Custom_zpsw8apqkxi.jpg.html)

lakeside53
03-04-2015, 10:23 PM
Ready for assembly? - fat chance!

Looking at the spindle threads, I had noticed they looked a bit wide on the top flats but figured they has just relieved them more to stop damage. They measured about at about 1.475 inches, a bit low but "ok". After all... I has a nose protector nut and back plate that screwed on nicely. On a whim I grabbed a 4-jaw check with a 1.5-8 backing plate. Wouldn't screw on at all! Grabbed two more - same deal. WTF? Check again , maybe some wacky metric/whatever thread - nope, 8tpi...

Decided to get technical. No thread wires so I checked all my #50 drills shanks until I found three that were exactly 0.0700. Probably not perfectly round but good enough for a quick test.

For a class 2A 1 1/2-8 using 0.0700 wires, I'd expect 1.5184 to 1.5111. My measurement was 1.529. Now it was obvious... it wasn't that the thread tops were cut down - they weren't finished to the correct depth!. Argghh.. worse, they supplied a nut and faceplate that fitted nicely, but not standard. I bet they made a run of beautiful but messed up spindles and decided to "fix" it by supplying two matching parts. lol

Thread calc I used. You can enter any wire sizes or select the class. http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

File test shows it's not real hard (probably RC28-32 if 4140ph) so I'm going to try to recut them. I've wrapped the roller bearing with blue masking tape to keep the junk out.

First, dial in the set-tru for zero run out (I could have used soft jaws also).

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2150%20crop%20Custom_zpsh5rypzyb.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2150%20crop%20Custom_zpsh5rypzyb.jpg.html)


Then a bunch of mucking around getting the existing thread synched to the feed. A few trial passes and I'm ready. Damn, things go by real fast at 80rpm on 8tpi. Sure glad I had my carriage limit switch to cut the spindle and apply the brake. I used a 16ER8UNJ full profile insert. I'll end up with a nice radiused root also. Ok.. adjust depth to skim the old thread.. looking good.. 3 thou more... nice... BANG. Busted off the insert on a hard spot near the shoulder end of thread. Reset the set-tru again, rotate the insert, sync to the old thread, dig out parts of the old insert from the spindle and skim again. Sneak up a few thou at a time and all is well. the ER insert are razor sharp, and really strong in the larger profiles so no issues with shaving even at low sfm.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2153%20Custom_zpsq2lmfwhv.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2153%20Custom_zpsq2lmfwhv.jpg.html)

Recheck with wires; spot on (my target) - 1.517. Grab my other chucks and they are thread on beautifully. Whew... Oh.. note the bed cloth to catch the thread wires when they try to hide in the swarf tray...


The endplay adjustment part has a setscrew to lock it. That screw misses the smooth zone and mangles the thread. Need to fix that.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2187crop%20Custom_zpsmcip2klo.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2187crop%20Custom_zpsmcip2klo.jpg.html)

Done. Yes, didn't have much of a hold on the part!
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2188crop%20Custom_zpstqidwmxe.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2188crop%20Custom_zpstqidwmxe.jpg.html)


Ready for reassembly.

lakeside53
03-04-2015, 10:23 PM
Main castings back together (easier to hold and work on if the rotating casting is in the cradle). Spindle greased, gear mounted and ready for insertion.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2183%20Custom_zps9unqkrwx.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2183%20Custom_zps9unqkrwx.jpg.html)

Rear thrust bearing and locking nut. Because I took about 80 thou out of the casting, I need to build that up again. Turns out the bearing thrust plates are 1mm thick, so the two old plates (including the cracked one!) went into the hole before the new thrust bearing. Perfect!

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2184crop%20Custom_zpsctazta61.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2184crop%20Custom_zpsctazta61.jpg.html)

Now the worm assembly and endplay/backlash adjuster.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2191%20Custom_zpsazlsgtlj.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2191%20Custom_zpsazlsgtlj.jpg.html)

Inserted. This is a good time to adjust the spindle preload - you can't do it with the worm gear engaged. I have a nice Famco tool to adjust the nut, but you can make something really easy with two bolts and a disc. I've moved the eccentric worm mount to the disengaged position for the next picture to enable spindle preload adjustment. Tighten until you feel the spindle just start to bind, then back off a tiny amount and tighten the lock screw,

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2192%20Custom_zpshcbluo3b.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2192%20Custom_zpshcbluo3b.jpg.html)

Move the worm eccentric such that the worm fully meshes with the gear then back a tad. Tighten the backlash/endplay while rotating the worm so it all moves freely with minimal backlash. By juggling the worm mesh position and shaft endplay, you can pretty much get rid of all backlash if everything is in good shape. Over do it and you'll end up prematurely wearing the bronze gear

That's it - all done... I'm happy with the outcome. A zillion things could have gone wrong when I recut the spindle threads, but they didn't. lol.

Next. CNC Stepper control of the handle so I don't have to mess with counting rotations and remainders, but that will be another thread.

gbritnell
03-05-2015, 08:19 AM
Great job and write-up! I too have one of these clone dividing heads, mine made by Vertex. It had almost the identical maladies that your's had. The only additional imperfection that mine has is at one point in the main gear it's just a tiny bit snugger than the rest of the rotation. Oh yes, I had to file the bronze sector arms because the didn't sit flat against each other.
Isn't it curious how they can take a good tool apart, reverse engineer it and then make it crappy!
gbritnell

justanengineer
03-05-2015, 08:56 AM
Isn't it curious how they can take a good tool apart, reverse engineer it and then make it crappy!


Welcome to my world, you'd likely laugh until you cried if you spent a day in my office. The biggest problem with reverse engineering is that folks not only feel the need to copy, but also to "improve." Not that the improvements in this case necessarily caused the manufacturing issues, but they sure didnt help simplify things....KISS is my motto.

PixMan
03-05-2015, 09:16 AM
Great work and a nice upgrade to the dividing head! I probably wouldn't have got that far into it, or at least that's what I'm telling myself.

One thing I noticed right away, which has nothing to do with the work, is that I have the same Mitutoyo 1-2" micrometer and just love it. Mine also was reading without the "1" in front of the decimal but after I played with the buttons and battery and eventually did get the full reading back.

Stepside
03-05-2015, 09:22 AM
Nice write up and a piece of Garbage turned into Gold. I have two small dividing heads, both bought used and abused. The first one had not been lubricated for so long that the grease was some powdery clay like substance that was a pain to remove. After a complete tear-down it is a nice tool. The second one was owned by someone with a 15 inch Crescent Wrench and a 3 pound Drilling hammer. After a complete tear-down and some home made parts it too is sweet.

In both cases they had been on the shelf for a while and the rebuild was because of a Need To Use situation.

lakeside53
03-05-2015, 10:42 AM
Great work and a nice upgrade to the dividing head! I probably wouldn't have got that far into it, or at least that's what I'm telling myself.

One thing I noticed right away, which has nothing to do with the work, is that I have the same Mitutoyo 1-2" micrometer and just love it. Mine also was reading without the "1" in front of the decimal but after I played with the buttons and battery and eventually did get the full reading back.

I hadn't changed the battery for years (ever?) and the display was a bit dull. After changing it and putting in the reference measure, I pressed something wrong and it up and didn't have time to figure out how to get the offset back. Guess I should read the instructions :)

lakeside53
03-05-2015, 10:47 AM
Great job and write-up! I too have one of these clone dividing heads, mine made by Vertex. It had almost the identical maladies that your's had. The only additional imperfection that mine has is at one point in the main gear it's just a tiny bit snugger than the rest of the rotation. Oh yes, I had to file the bronze sector arms because the didn't sit flat against each other.
Isn't it curious how they can take a good tool apart, reverse engineer it and then make it crappy!
gbritnell


yep.. I found one more thing that need attention : the o-ring that holds the bronze arms from slipping can't go into the groove because the arms are too thick. I'll need to cut a recess grove into the outer arm.

Oh, my main gear/worm is a bit tighter at one point also! Some tiny run out somewhere that make it hard to have zero backlash at all points.

duckman
03-05-2015, 10:57 AM
Lakeside I just have to ask how do you measure the threads with .700" wires (or just a typo).

lakeside53
03-05-2015, 11:04 AM
You can use any wire size with a certain range for a given thread. In the my case of 1 1/2-8UN, that's 0.0700 to 0.1125. You either do a bunch of math or... use this online calc.

http://theoreticalmachinist.com/Threads_UnifiedImperial.asp

This calculator is really good - you can use the drop-down box for wire sizes (and it will give you the min-max useable), or you can type in any arbitrary size. I did not have any wires at that time, so I improvised with #50 drill shanks. I now have wires, until I lose the one I need ;)

You can buy the apps(s) for you phone too.


For those that haven't used wires before, if you weren't born with 5 hands the the "secret" is to simply put sticky grease on the threads to hold them. But do use a catch cloth - they are almost invisible in you lathe chip tray, especially if it's 6 inches deep of crap like mine.

gbritnell
03-05-2015, 12:47 PM
Actually my sector arms are held in place by a c-clip made from spring steel. It has a bow to it so it keeps pressure on the arms to keep them from turning when you rotate the handle. We had a B&S in our shop and it had the same type of spring clip. I can take a picture If you like.
gbritnell

Toolguy
03-05-2015, 12:58 PM
I just poke them into a piece of closed cell foam, guided by the threads they are going across. No mess, no juggling act.

PixMan
03-05-2015, 01:05 PM
You can use any wire size with a certain range for a given thread. In the my case of 1 1/2-8UN, that's 0.7000 to 0.1125. You either do a bunch of math or... use this online calc.



I think you've got the same typo TWICE now.

Shouldn't that be a 0.0700" wire, not .7000?

ncjeeper
03-05-2015, 01:29 PM
Nice write up. Thanks for sharing.

John Stevenson
03-05-2015, 03:55 PM
Next. CNC Stepper control of the handle so I don't have to mess with counting rotations and remainders, but that will be another thread.

Snap.
Just picked a brand new unit up this week, still in all it's packing grease and that is destined for a stepper drive.
Already have an identical unit done ages ago so probably strip this to remind me what i did and do the same to this new unit.

It's on this page http://divisionmaster.co.uk/divisionmaster.html
Under examples of use but that was an early mod, later mod has a different motor but everything else is the same.

Alistair Hosie
03-05-2015, 03:59 PM
You did a great job brother!Many thanks for the posting and the many photo's too.great thread Alistair

lakeside53
03-05-2015, 04:08 PM
I think you've got the same typo TWICE now.

Shouldn't that be a 0.0700" wire, not .7000?

lol.. sorry all.... yep. typo - I meant 0.07000 Hey.. I did pretty good. Just had my colonoscopy (good news) and was prepping all day yesterday and last night. Urgghh.! I'll go back and fix the other posts.

lakeside53
03-05-2015, 04:11 PM
Actually my sector arms are held in place by a c-clip made from spring steel. It has a bow to it so it keeps pressure on the arms to keep them from turning when you rotate the handle. We had a B&S in our shop and it had the same type of spring clip. I can take a picture If you like.
gbritnell

Yes, I'd like that picture!

lakeside53
03-25-2015, 11:46 PM
OK... Couldn't bring myself to use the head as is - the cast iron grit from gear cutting would get into the main roller bearing.

There about a 1/16th gap around the flange and that is directly onto the bearing rollers. Sure, there's normally a big direct index disk over that area, but that's a 14mm gap open to junk. And cast iron dust will get everywhere.

The problem:

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2225%20Custom_zpsg8m8tych.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2225%20Custom_zpsg8m8tych.jpg.html)

The solution - a shaft seal. The rotating hub (in my case) is exactly 75mm, so a 75x95x5 fits perfectly. I could have slapped it on and stopped right there - it would have been better, but best to make a retainer to hold it in place.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2226%20Custom_zpscj970fyd.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2226%20Custom_zpscj970fyd.jpg.html)

I have a cnc BP, so that will save me mucking around on the lathe or with rotary tables, and I can put fancy curves on the mount tabs. Many ways to do this, including a lathe.

In my case, this CNC conversion has a geometry calculator built in so I didn't need to draw anything in cad. Took about 45 minutes to get this right.

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2227%20Custom_zpsaicswqld.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2227%20Custom_zpsaicswqld.jpg.html)

Ready to make chips:

Face off the block (I used a scrap of 7075).
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2228%20Custom_zpsid17hmvx.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2228%20Custom_zpsid17hmvx.jpg.html)

lakeside53
03-25-2015, 11:47 PM
Time to make a real mess. Lots of WD40.. smoking... chip everywhere

http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2229%20Custom_zpsr3zyn1iz.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2229%20Custom_zpsr3zyn1iz.jpg.html)

Bottom side cut out.
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2236%20Custom_zps5eyd6qgp.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2236%20Custom_zps5eyd6qgp.jpg.html)

Now to flip it over, mill off the holding plate and bore the countersinks for the SHCS. It's a weird shape to hold but with cnc you can just move the cutter from "inside" to "outside" and mill out some soft jaws. Takes less time to mill than changing the jaws! These have been used a few times before.
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2237%20Custom_zpscc8uug2e.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2237%20Custom_zpscc8uug2e.jpg.html)

After milling off the holding plate and boring the countersinks.
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2238%20Custom_zpsfnsvxrj3.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2238%20Custom_zpsfnsvxrj3.jpg.html)

lakeside53
03-25-2015, 11:48 PM
Test fit of the seal in the retainer.
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2241%20Custom_zpsu5uiqsk1.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2241%20Custom_zpsu5uiqsk1.jpg.html)

Drilling and threading holes (for 8-32) in the head. I used the retainer and seal to keep the swarf out of the bearings.
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2245%20Custom_zpsref1rqxl.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2245%20Custom_zpsref1rqxl.jpg.html)

Mounted (well greased beneath).
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2247%20Custom_zpsgvcxrqwn.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2247%20Custom_zpsgvcxrqwn.jpg.html)

Fixed index plate remounted and ready to use!
http://i238.photobucket.com/albums/ff150/lakeside53/BS1%20clone%20dividing%20head%20reworking/DSC_2250%20Custom_zpsy7ha2out.jpg (http://s238.photobucket.com/user/lakeside53/media/BS1%20clone%20dividing%20head%20reworking/DSC_2250%20Custom_zpsy7ha2out.jpg.html)

The seal gives a nice drag - that will work to advantage with the backlash.

Now to cut gears...

metalmagpie
03-26-2015, 12:37 AM
Very nice .. that sow's ear is turning into a silk purse!

metalmagpie

Paul Alciatore
03-26-2015, 06:02 PM
Great job and very good write up. Thanks for sharing.