# Quill DRO for a PM935?



## Alan H. (Jun 27, 2017)

Tired of not having a DRO on the quill of my PM935TV.  I am sure that others have solved this problem.  

Can you share what you did and any insights please?


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## bfd (Jun 27, 2017)

you can find a separate dro for the quill its like a digital caliper turned sideways. mitutoyo has one but its costly I got mine for about 40 bucks made a quick mount and I just need to remember to turn it off or barrery replacement time they come in 5" and 6" lengths . they are cuttable with no damage. just make sure the cut is in the mount not used.  I got mine at a local tool store. this store sold machinist tools. If I knew how to post pictures I would bill


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## Alan H. (Jun 28, 2017)

Photos of an install would be appreciated.

Anyone pony up for a Mitutoyo and install it on a PM935?


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## Rich V (Jun 28, 2017)

ABOM79 did a youtube vid on installing the Mitutoya quill kit. Same basics for doing it on the PM935


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## Alan H. (Jun 28, 2017)

Thanks Rich, had all I needed to see.   

Has anyone put one of these kits on a PM935?   I am assuming it would fit but would like confirmation.


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## Alan H. (Jul 5, 2017)

After studying the options, I installed a Mitutoyo Quill DRO kit on my PM935 mill.  I acquired it on sale at Zoro for a decent price.  The kit is for a Bridgeport or clone.

The install went reasonably well but did require a few tweaks to get it  “right and tight”.  I am sharing some of the details with some photos in case it may help someone who decides to go this route.

While the kit comes with instructions and a very good parts list, Adam’s (ABOM79) YouTube on mounting a kit on a Bridgeport was very helpful to familiarize one with the kit and how it mounts.

The kit came with all the hardware needed with the exception of two mounting screws needed for my PM935 install.

Here is a list of the things I did to make it fit and make the install better for my particular mill.   This list is not intended to be all inclusive and one should confirm that the dimensions of your mill would require everything I did or perhaps something different.

Tweaks and insights:

I had to chase the small M3 threads in the mounting frame – the powder coat had choked the threads.

I had to countersink the holes on the back of sending unit mounting plate to accommodate the included #5 gun screws.  Screws were too short as supplied to get proper thread engagement.  I could have ordered proper length screws from McMaster but decided to simply use what I had and milled a step for them to sit in.





I milled off .060”of mounting bar to move the assembly closer to mill and to maximize the insertion of the mounting tube into the stop ring on the mill.




I bought two new mounting screws to attach the mounting bar (M4 x 12), one had to be ground slightly shorter to not interfere with the power feed mechanism.  I did not leave the depth scale on the machine as called for in the instructions.  I found this to not be needed for spacing nor add any functionality since the scale was covered if left in place.




I shimmed the mounting tube to the mill’s stop ring joint to take up .010” of slack in the fit.  This allowed the set screw to expand the mounting tube to a good firm fit and eliminate any wiggle in the joint.  You can see the copper shim wrapped on the split tube in this photo. This shimming avoids the wiggle that ABOM79’s video shows.   Thanks to Adam for making the YouTube since it catalyzed me shimming the tube/stop joint in the initial install and making it rock solid.







All in all a very good fit and function with just a little adapting and tuning.  There's still plenty of room behind the Mitutoyo for the original depth stop function to be adjusted and work well.   I can still put my depth stop clamp on the rod as well.  Although many folks keep them removed anyway, the front fine feed crank/wheel also still fits without interference.

Hope this may help others if you decide to go this route.  Here is the unit installed on my PM935TV.


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## Rich V (Jul 6, 2017)

Looks great Alan!


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## [X]Outlaw (Jul 7, 2017)

Looks great! Thanks for the detailed write up.


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## MonkMan (Jul 7, 2017)

Thanks, this just made it to the top of my (very long) list!


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## Alan H. (Jul 7, 2017)

Rich V said:


> Looks great Alan!


Rich, thanks for posting Adam's YouTube.  I had missed that one somehow.  It was helpful and pushed me forward in buying the Mitutoyo kit.   As I pointed out above, it also clued me in on the wiggle issue and to be prepared to address it.


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## Alan H. (Sep 27, 2017)

*"WARNING"*
Follow-up on the installation I did - 

*I did not get the mounting screws for the Mitutoyo mounting bar short enough.*  The mounting bar uses the same holes as the factory depth scale for installation.   The factory scale is mounted over the Auto Feed mechanism (see pg 14 of the PM manual).  While I did not believe the bottom screw was interfering with the trip push rod that locks the "Quill Auto Feed Lever", turned out that it actually was interfering just enough to cause a problem. 

While everything appeared to be fine, the screw was just long enough to bind the "Trip Push Rod" itself and the "Quill Auto Feed Lever" would not lock and hold position.   Lesson learned - _Make sure that screw is short enough that it will not infringe onto the trip push rod._

As always, Matt at QMT was ready and willing to help but it turns out that I had laid a trap for the both of us and I wasted Matt's time.  Sorry Matt!

Trip Push Rod schematic:




Here's a photo of the mounting bar in place with the two screws in the original attachment points for the factory depth scale.  Size the length of  this screw to not interfere with the function of the Trip Push Rod (#5 in schematic above):


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## [X]Outlaw (Sep 27, 2017)

Thanks for posting this! I'm picking up my DRO kit tomorrow and hoping to install it over the weekend. Between Abom79 video and this thread I think all the "gotchas" are well covered.


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## petertha (Nov 15, 2018)

Apologies, I posted elsewhere on 935 quill DRO & then found this post specific to the Mitutoyo model 053906 (sometimes B on end?).
I'm relatively sold on the Mitutoyo, mostly because it happens to be on sale right now! But I've noticed I have not seen a picture of the DRO in conjunction with the down feed hand wheel. Is that because people just don't use the hand wheel much, or the DRO conflicts with it?


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## [X]Outlaw (Nov 16, 2018)

I don't have a pic right now but the DRO in no way conflicts with the handwheel.


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## davidpbest (Nov 17, 2018)

The Mitutoyo Quill kit is ok, it works, doesn't impinge on the downfeed crank-handle.   That said, I prefer to make my own mounting brackets, which you've probably already seen  (  LOL  ):  https://flic.kr/s/aHsmpXogeF


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## petertha (Nov 17, 2018)

_ ...which you've probably already seen..._
Oh-Ya! 
David, with your integrated set screw micro-adjusters, does it lend itself to running a test indicator up the face & edge of Mitutoyo scale on quill movement, kind of like dialing in your XYZ DRO scales? Or is it mostly about dealing with casting variations & geometry in general? Any general words of wisdom re drilling & tapping cast iron for bracket items like this?


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## davidpbest (Nov 17, 2018)

Peter, please realize that the primary reason I ditched the Mitutoyo supplied quill mounting bracket system is because I needed to integrate a proximity sensor into the quill DRO encoder mounting system.   This proximity sensor triggers an auto-reverse when the sensor detects the quill stop, and is handy for threading operations.  Thank you Mark Jacobs.

If I had not needed to add the proximity sensor, I might have used the Mitutoyo supplied bracket system, modified along the lines of what Alan H did.

If you do decide to make your own brackets, here are some tips.    First, be very careful where and how deep you drill and tap the head casting for mounting screws.   You're working in an area where the power downfeed trip mechanisms are buried inside the casting.   See this for more info:  https://flic.kr/s/aHsmq2F8fj

The other thing is that if the Mitutoyo scale is not precisely aligned and kept flat, the encoder part (which is attached to the traveling doughnut ring) will drag on the scale enough to add friction to the quill movement, defeating the auto-retract spring no matter how much you tension the retract spring.    That was the purpose of the jacking set screws in my bracket design - to be able to tweak the angle and casting offset for each scale end. 

There is no practical way to check the alignment of the scale part using an indicator or similar - it's a matter of fussy trial and error, and to get all the friction of the Mitutoyo DRO dialed out of the system, it took me a couple of hours tweaking things.   Since I didn't install the Mitutoyo bracket, I have no idea if it's easy or fussy in this regard.

Hope this helps.


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## Boxster9 (Nov 22, 2018)

David your projects are always a joy to behold. Thanks for sharing your thoughtfully and well engineered ideas. Coupled with the magic of Mark Jacobs and its Wow!  You both deserve a heartfelt thanks for sharing and enlightening the rest of us.


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## petertha (Nov 23, 2018)

OK, here goes with my installation. I will preface this by saying - what a weird piece of kit! Kind of a puzzling assortment of hardware & bits of pieces with no clear instructions as to what they are for. Unlike the proverbial Ikea furniture build, I had hardware left over! Recognize there may be variations to '935' mills out there. Also I am no expert. I'll run it this way for a while & if I see things I don't like, I'll report back.


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## petertha (Nov 23, 2018)

My stock rule scale was removed & exposed M4 screws & threaded holes in the casting. Similar to others, my screws did not have sufficient clearance in the slot so cleaned up the aluminum bar with 4mm end mill. Found center & took off about .007" on either side, just enough to give the shank clearance. It wasn't just anodizing buildup, the slot itself wasn't cut so great.

I measure how much the stock screws protruded into the casting & ended up using M4x10mm cap screws to give me the same penetration. Someone pointed out if the lower one goes in too deep, it can mess up the down feed mechanism. Thanks for that heads up!


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## petertha (Nov 23, 2018)

Issue 1 was the block that holds the round stem & gets mounted to the DRO back. It took me a while to figure out what was going on - it just didnt fit nice to the DRO display unit. First I increased the depth of 90-deg countersink because the 2 flatheads protruded above & plate would not sit flush.

The plate itself is mounted with four 5-40 screws which is a WTF choice of bolt, at least for my inventory. Why not M3? Why not 4-40? The SR# label sticker raises the back a couple thou & yes this makes a difference of how the crazy thing wants to be mounted. If you over tighten, it can bind the sliding action. If you loosen it too much, well, you've lost some of your 2 threads of engagement. At some point I'm going to back & either blue locktite my current setup or 'ever so slightly' counter bore so the heads are slightly recessed like someone else did. Nope, I didn't want to re-tap the stainless DRO back! LOL. There are some strange stickers that come in the kit which I thought might be for shimming but I couldn't figure them out. I just experimented with tape until I had the right fit. This was some kapton I had laying around.

Nope the washers don't appear to be for standoff on the back face of DRO. And if you install them between bolt head & plate, the screws dont engage. Hmm....?


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## petertha (Nov 23, 2018)

Trial fit #1. I installed the assembly the way it looked in instructions & I had about 0.1" gap. I suspect this might be normal, someone else milled the bar thickness down which is one option. The bigger issue is that the stem does not get much penetration into the donut looking depth collar. So I put the scale on the opposite side of the metal frame bar to net me the distance. Since it gets pre-assembled anyway, I didn't really see any downside.

I also replaced the supplied 10-40 set screw with a normal cap screw & that allowed me easy & positive tightening with ball end hex wrench. The set screw is a royal pita.


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## petertha (Nov 23, 2018)

I used pop can aluminum to make kind of a round shim collar between the clamp pin OD & the donut ID. I think it was about 0.005" That made for a nice slip fit & the tightening was just a quarter turn & it was solid


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## petertha (Nov 23, 2018)

To install I left all the fasteners just finger tight & got the DRO scale lined up close. Then I set up the mag base & indicated first on the front face ground edge, then on the side edge by extending & retracting the quill. After a few iterations its about 0.001" runout over travel & appears to be staying put nice & tight. Note you can bend the steel frame 'door handle' thing 10 thou just tugging on the cantilevered ends, so A) easy way to adjust the in/out  B) try not to bump the frame or if you do, run the indicator over it again.


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## petertha (Nov 23, 2018)

Here is my bass-akwards scale installation that actually seems to offer a few advantages over front mount.


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## petertha (Nov 23, 2018)

Final install. Yes the down feed 'captains wheel' handle fits too.


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## davidpbest (Nov 26, 2018)

Looks great.


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## Firstgear (Dec 22, 2018)

If anyone needs countersunk Allen screws 5-40 thread, I bought 100 and will be glad to send you some...PM me and I will give you an address to send a self addressed stamped envelope to....The screws are 0.5” long so you will need to shorten them up.


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## Firstgear (Dec 22, 2018)

This is what I bought...  https://www.amazon.com/Socket-Screw...F8&qid=1545505997&sr=8-15&keywords=5-40+screw


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## kb58 (Jan 19, 2019)

This thread brings up something I hadn't thought of:
With a knee mill, how is a hole in the work bored? DRO sensors are typically on the knee, which implies that the knee controls the cutter feed. The thing is, most quills have a fine feed lever (much more fine than the knee handle), which seems to imply _that's _what's supposed to feed the cutter into the work. Which is it? My PM935 hasn't arrived yet, hence the question.


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## [X]Outlaw (Jan 19, 2019)

You can set your quill stop to your desired depth. When the stop is hit the quill auto down feed will disengage.


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## ddickey (Jan 19, 2019)

kb58 said:


> This thread brings up something I hadn't thought of:
> With a knee mill, how is a hole in the work bored? DRO sensors are typically on the knee, which implies that the knee controls the cutter feed. The thing is, most quills have a fine feed lever (much more fine than the knee handle), which seems to imply _that's _what's supposed to feed the cutter into the work. Which is it? My PM935 hasn't arrived yet, hence the question.


Depends. For larger drills raising the knee is the proper way I believe. There is no feel though using the knee as opposed to the quill so for small drill bits the quill is better. Other operations like end or face milling you use the knee.


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## Firstgear (Jan 19, 2019)

My PM950 has three axis DRO and one of them is on the knee.  I bought one of these to also have a DRO on the quill.  Overkill?  Yeah, maybe....


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## davidpbest (Jan 19, 2019)

I would not be without a DRO on the quill.  I have a 3-axis Newall DRO on my PM935 including the knee.  Details here:

https://flickr.com/photos/53698949@N05/sets/72157700369813974

But for the quill I prefer a digital scale with integral display - easier to watch progress when tapping than having the display off to a side-mounted display head.  So I also added a Mitutoyo DRO on the quill.  Details here:  

https://flickr.com/photos/53698949@N05/sets/72157699692406901

Having a quill DRO is very helpful when setting the quill power feed depth stop for counterbores, countersink, boring, etc.  Yes, you can use the knee with DRO for large drilling ops, but I find it less convenient than using the quill most of the time, and the quill is better for power feeding ops since it has a depth stop and the knee does not.


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