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PM-727m New mill has arrived!

Discussion in 'PRECISION-MATTHEWS' started by Sloth2009, Mar 27, 2017.

  1. Sloth2009

    Sloth2009 United States Active Member Active Member

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    IMG_5166.JPG IMG_5177.JPG IMG_5178.JPG Playing around with HSS. My one previous bit grind didn't cut too well with a fly cutter on Al. I realized I hadn't cut in a rake angle at all so I reground and added one. I am also now wondering about the nose radius? Is it too small? Any grinding suggestions?
     
  2. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Nose radius can be small or large, as needed. First, you should always have a radius, even if it is very small. Otherwise the tool will chip. A small radius is good when you want to push the tool less hard. That might be to minimize deflection on a long and slender part, or when your machine is under powered. A big radius is for a good surface finish, or to make a large radius corner. If your machine or setup is not rigid enough to power the larger cutting area, you may get chatter, or bog down the lathe if it is not powerful enough. That is a nice thing about HSS tooling. You can easily make the tool match the circumstances, and keep tweaking it until it works good.
     
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  3. Sloth2009

    Sloth2009 United States Active Member Active Member

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    My powered x-axis is still on back order from PM. I decided to cancel that for now and ordered the 3 axis Dro through PM. I think it will be money well spent. I have next week off. I plan to do the epoxy tram on the column. Wish me luck.
     
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  4. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Oh. I got my aluminum t-slot covers today and fit them in. Oddly the t-slot in the front of my table is slightly wider than the back 2 and the covers fall through. I just stacked 2 covers on top of one another and they fit perfectly. The way covers slide pretty easily. I may put a little tape on the side of them to increase their staying power. IMG_5184.JPG IMG_5187.JPG IMG_5188.JPG IMG_5189.JPG
     
  5. Sloth2009

    Sloth2009 United States Active Member Active Member

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    IMG_5125.JPG IMG_5209.JPG The placement of the wires on the back of the pm727m switch box are annoying to say the least. They are right in the way of the z-axis locks and of one of the head locking bolts. I bought some 90 degree cable glans to change the output direction of the wires, but realized there is an even easier fix. Simply turn the power box back plate upside down! I may add a small eye bolt to the back of the colum or something similar to guide the power cord as the head moves up and down.
     
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  6. fradish

    fradish United States Active Member Active Member

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    Turning the backplate upside down is a good idea (which of course I didn't think of...) :)

    I made round aluminum knobs for my z-axis locks because I was running into the same issue.
    Plus I'm not a fan of the spring loaded locking levers that come on the mill. I even prefer the
    hinged locks on the y-axis to the spring loaded locks. Just a personal preference.

    I've replaced my x-axis locks too as they would sometimes interfere with the base. I've never
    found that I needed to tighten these more than hand-tight, but even if I did I used socket
    head cap screws so I can tighten them with a hex wrench if I ever need more leverage.
     
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  7. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Well... I did the epoxy tram today. Now time to wait 24 hours and do some testing. Here is an outline of the process I used.


    PM-727m DWH Epoxy Tram

    Phase 1: Initial Setup

    Buy and install 4 longer 12mm bolts
    Pull mill from wall for 360 deg access
    Level table by adjusting mobile base
    Clean machine and chip tray of chips and oil
    Remove way covers
    Loosen bolts and rock column from front to back adding larger shims during each tilt
    Aim for at least 1" gap to make cleaning critical surfaces easier


    Phase 2: Critical surface Prep

    Clean mating surfaces and around column base
    Wipe down with isopropyl alcohol and acetone
    Scrape off any paint or Chinese putty
    Use 120g sandpaper to roughen critical surfaces
    Clean critical surfaces again with acetone
    Install at least 2'layers of double sided foam tape to prevent epoxy from leaking to inside of column


    Phase 3: Gap setup

    Lower column to about 1/2" gap
    Install original bolts
    Install 2 copper crush washers on each bolt
    gap = 0.090" good thickness for DWH
    Lower column onto copper washers
    Lightly snug down bolts


    Phase 4: Masking off

    Clean areas to be masked off
    Tape off large gaps in front rear of column with painters tape
    Tape and off column, base and chip tray where needed


    Phase 5: Epoxy injection

    Install test indicator and tram column roughly to table
    Temperature ok for epoxy?
    Mix epoxy and hardner for 3 minutes
    Inject prepared epoxy evenly into gap
    Tape gaps to keep epoxy from running out
    Tram z to table with square using column bolts to change tram
    Do y axis 1st then x... then y again.
    Be as precise as possible especially in y-axis
    Let cure 24 hours



    IMG_5227.JPG IMG_5229.JPG IMG_5230.JPG IMG_5232.JPG IMG_5237.JPG IMG_5241.JPG IMG_5242.JPG IMG_5245.JPG IMG_5247.JPG IMG_5248.JPG IMG_5259.JPG IMG_5261.JPG
     
    Last edited: Apr 24, 2017
  8. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Curious if you used any kind of mold release on one side of the mating surfaces you epoxied in case you ever want or need to remove the column?
     
  9. Sloth2009

    Sloth2009 United States Active Member Active Member

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    No I ended up deciding against it. I did think about it quite a bit. I originally wanted to wax or teflon grease just the bottom of the column so it could be separated if needed.

    First I figured it would be fairly difficult to get a thin even layer of release on the upside down surface without some way to lift the column completely off the base. I did this tram 100% myself with only manpower, so it was difficult already. Second, I thought the adhesion of the epoxy to both surfaces would add some more strength in tension as well as compression at the joint. Essentially adding stronger and more even downward holding power than the mounting bolts alone. I'm still not entirely convinced that line of thinking is correct and I may regret it later. It definitely made the tramming a bit more stressful.

    I ended up not filling the gap in the front of the column. I couldn't get the syringe in the right place to inject. I could fill this in later if I want, or leave it open in case I need to go at it with a crowbar. :eagerness:

    At this point there are a few things I would have done differently. I should have found a short thin piece of tubing to attach to the syringe tip. The syringe tip by itself was too short and wide to fit very far into the gap. I also would cover all the gaps in strong clear packing tape before injection. Poke a small hole in it with a screw, inject through the hole, then tape it back up when done. I figured this out 3/4 the way through injecting after making a mess. 3 or 4 injection holes along each side would do the trick. Make and plug the holes as you go to reduce mess. The clear tape lets you see the gap fill up as well. I used 2 50 DWH kits along with 2 injection syringes. With my mess, I just barely had enough to fill the 3 sides.
     
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  10. Sloth2009

    Sloth2009 United States Active Member Active Member

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    IMG_5270.JPG As a little side test, I lightly greased a HSS tool bit and shimmed it into my fly cutter. There was a slight gap at one end due to poor machining. When I mixed up the epoxy earlier I squirted a tiny bit in the gap. I just checked it out and it seemed to have worked pretty well. I think I will wait the full cure time to check out the mill though.:wink:
     
  11. Greebles

    Greebles United States Active Member Active Member

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    Nice write up. Having this increases my confidence in doing this for myself. However I think I would have used mold release on both mating surfaces.

    -Denzil
     
  12. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Overall I am satisfied with the epoxy tram results. The y axis was a bit out when I first measured this morning. Maybe my precision square is not so square. There was just enough adjustability left in the mounting bolts to get it on track. Right now from spindle to table my x and y are both measuring about 0.0005 difference over 6.5". Here is a picture of the epoxied gap after removing all the tape. Its a bit messy, but turned out ok. IMG_5273.JPG
     
  13. Sloth2009

    Sloth2009 United States Active Member Active Member

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    I don't think you need to be afraid of this stuff if something goes wrong. I let some do a full cure on a stick and drilled through it with a drill press with no problem. If you had to undo an epoxy tram you could drill around the gap with a small bit until the column breaks loose. Then you could grind it off and reapply as needed. IMG_5271.JPG IMG_5272.JPG
     
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  14. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Got the 3-axis dro from PM today. They were about $450 and are supposed to be good down to 0.0002. I had never even seen a dro before so was a bit overwhelmed with all the pieces and parts. There is not much help in the paperwork to tell you how to install them. I did a little research and familiarizing myself with the parts and I think I have a decent handle on it now. I will go buy some standard bolts tomorrow for the mounts so I don't have to buy find a metric tap. If all goes well I will install them tomorrow afternoon. IMG_5275.JPG IMG_5279.JPG
     
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  15. Greebles

    Greebles United States Active Member Active Member

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    I have installed this very same DRO on my PM-727. I can provide photos of my install and answer any questions you need.

    -Denzil
     
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  16. wrmiller

    wrmiller Chief Tinkerer H-M Supporter-Premium

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    Yea, the first install can be a bit overwhelming. But then after you get it done, you realize it wasn't so bad. I studied a lot of the pictures on DroPros website before I did mine. Still ended up doing it over. :rolleyes:

    Greebles is willing to help, and has the same mill. That should help considerably. Have fun. :)
     
  17. Sloth2009

    Sloth2009 United States Active Member Active Member

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    I would love some pics, esp of where you mounted the reader and its mounting bracket on the x and y axis. Is your y-axis dro on the right hand side? Does it get in the way of the gib locks? Would you have done anything differently?
     
    Last edited: Apr 27, 2017
  18. Greebles

    Greebles United States Active Member Active Member

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    I installed the Y-Axis on the left side of the machine to prevent interference with the Y Locks and mounted the X Axis reader to the front.

    Make sure you measure and mark the table and saddle travel before you begin. In the pictures below you will notice green marks (lines) where I did that. This allowed me to make sure I aligned the scales and readers properly to allow for full travel (allowing for extra travel on each end for safety).

    [​IMG]
    Here you can see the X-Axis scale is mounted to the table using the dove tale track that was already machined into the table. The Scale Reader is mounted to the saddle with an L bracket.

    [​IMG]
    I marked the center of the saddle along the X and drilled / tapped two holes (10-32). They are the two lower horizontal holes.

    [​IMG]
    Y-Axis mounting was more work. On the left side of the machine I made a standoff that I mounted to the casting with two countersunk cap screws. I drilled tapped holes into this standoff for mounting another bracket to extend out over the base casting.

    [​IMG]

    [​IMG]

    -Denzil
     
  19. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Thank you for the pics!
     
    Last edited: Apr 27, 2017
  20. Sloth2009

    Sloth2009 United States Active Member Active Member

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    IMG_5285.JPG IMG_5286.JPG IMG_5287.JPG IMG_5288.JPG IMG_5289.JPG IMG_5290.JPG

    Im pretty much done installing the dro. I did the z and x axis yesterday and finished the y axis today. I still need to so some cord management and test the scales for linearity and accuracy. I did indicate in the mounting plates for the scales so should be pretty good overall. Everything powers up and outputs to the monitor which is good.

    Denzil's y-axis install would be the way to go. I asked Matt why they put their install on the right side and he said it is only due to convention, but there is no reason to do it on this mill. I made more work for myself and put it on the right side with a bracket off the back of the table for the reader. This avoids crowding the gib locks.

    For the x-axis I fabricated a bracket and mounted the assmebly to the back of the table. This should give me enough room to reattach the way covers.

    Half the mounting brackets are modified in some way. I also made a bracket for the swing arm so I could get it higher on the column. All my tapped holes are 10-32. I center punched, pilot drilled and used a drill/tap combo bit in a dewalt drill to tap the holes.
     
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  21. Redmech

    Redmech United States Active Member Active Member

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    Great thread, lots of good info I'm going to study
     
  22. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Just for giggles, I took the back panel into a car paint store and had them make me up a can of matching aerosol paint. I sprayed some on some foil and let it thicken up a bit. I then used a small brush to fill in all the little paint dings around the machine. I did a pretty shoddy job with the bondo and painting on the column but it looks better than it did. IMG_5304.JPG IMG_5306.JPG IMG_5308.JPG
     
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  23. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Not exactly milling with precision, but I used the mill to create the inside cavity in a wood sheath and handle for a sword I forged. The wood is from an ash wheelbarrow handle that I cut down the middle then glued back together after I milled it. Still a lot of work to do to make it look pretty. IMG_5339.JPG IMG_5340.JPG IMG_5341.JPG
     
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  24. Sloth2009

    Sloth2009 United States Active Member Active Member

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    IMG_5347.JPG IMG_5348.JPG
    Bought some M8x25 replacement knobs for the lockdown levers. The stock front levers tend to catch when you move the x-axis if you don't have them set perfectly.
     
    Last edited: May 4, 2017
  25. Sloth2009

    Sloth2009 United States Active Member Active Member

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    I also bought a project box, cut some holes into it and mounted it to the back of the DRO display arm. I stuffed all the excess data cables into it to tidy them up a bit. Just need to tidy up a few more and it will be good to go. IMG_5360.JPG IMG_5361.JPG IMG_5363.JPG IMG_5364.JPG
     
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  26. Ironken

    Ironken United States Active Member Active Member

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    Genius! Do you get enough torque on the knobs to lock the table down?
     
  27. Sloth2009

    Sloth2009 United States Active Member Active Member

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    Last edited: May 4, 2017
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  28. Sloth2009

    Sloth2009 United States Active Member Active Member

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  29. TheGov

    TheGov Reserved Iron Registered Member

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    Since this is "the go to thread" on the 727, I've got a note, w/ pic, and a question.
    First the note, drained the gear oil today, again. Got curious, so vacuum filtered it to see the particulates. Oh boy... (see pic for what I mean).

    Now the question ...I changed the oil because I noticed a lot of play up and down on the quill when I use the fine adjustment. Has something gone bad, hence the metal debree? What/where should I look first to resolve the play issue?
    Side note, I'm going to completely flush the gear box this weekend.
     

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  30. TheGov

    TheGov Reserved Iron Registered Member

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    Those be some 'perty' knobs...
     

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