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CNC Router/plasma cutter
I had some Thompson linear rails laying around so I ordered up some heavy duty 3X3 Tslot extrusions. I machined plates to hold the extruded rails together and installed the Thompson rail and guides. I bought the racks and drilled them so that the teeth were just above the extrusions. I installed pinions on the stepper motors and installed two 452 oz in stepper motors on the Y axis 1 on ther X and 1 on the Z . The Z axis is a direct drive to a 5 tpi ballscrew. I finished the unit last fall and have it running quite nicely. I can get speeds up to 1700 IPM but have kept it down to 300 IPM. I have home switches on it and am using Mach3 with G203 step motor drivers.
3D Scanner Project
I am working with B.J. Rao to bring to market a low cost high speed 3D Scanner. The scanner will use a turntable that will rotate an object 360 degrees. While the object is being roated a low cost video camera records a laser line that is projected onto the object. This recording is played back into the scanner software and a file is created that is then loaded into a builder program. The builder program then converts the raw data into a object that can then be exported in many formats such as .stl and cloud points and well as other formats. e are very excited about the posible applications for this low cost scanning system.
Current Status of my Tree Mill
Journeyman 300 retrofit project
April 18, 2005
I am nearly done with the finals details on the Tree mill retrofit. The last big problem that I ran into was there was more than normal noise coming from the two speed gear and pulley driven spindle drive. So I took it apart and was surprised to see fiberglas insulation packed around the inside of the casting. There is a lube system that pumps oil to the countershaft pinon gear and the spindle backgear. Of course the fiberglass was saturated with oil. So I figured that it was added as a sound dampening. I removed it. While cleaning the spindle gear case I also noticed two things. 1. there was groove in the lower casting that looked like it was machined 2. there were metal chips at the tangent of the pinion and bull gear. When I removed the bull gear and cleaned it I found some significant pitting of some of the pressure side of the teeth caused apparently by water entering into the upper casting. This pitting was only on about 1/3 of the teeth. I checked and found that there were no replacement gears to be had. I also noticed that the back side of each tooth was fairly smooth. So I cleaned up the gear and decided to mount it upside down since the gear was nearly symetical from top to bottom thus I would have a new and better condition teeth in contact with the pinion that was in great shape. I ascertained that the groove in the bottom of the casting was caused by the machine not being properly reassembled at some point in its history. I noticed that the upper bearing retaining lock nut wasn't all the way on the shaft threads. While I had it diassembled I lapped the threads in so I could bottom the nut. When I reassembled the unit and test ran it I found it to be a lot quieter. In the high speed position where the bull gear is disengaged the only noise was normal motor noise. At 6600 RPM it really sounds like there is small turbine running. In low speed at about 1800 the gear noise is still there but drastically reduced. I only plan to use the machine about 10 hours a week so I think I will pass on having a new gear made. The only things left to do is to do some more cleaning and painting. I plan retain the existing electrial enclosures and after removing all the electronics weld in shelves for tool holders, cutters and other supplies. I think my $750 Ebay milling machine was worth the work put into it and I enjoyed and looked forward to getting all the "rode hard and put away wet problems" repaired and working like a good used but still with plenty of life left in it. Feb 10, 2005 When I cleaned up my $750 Tree mill Journeyman 300 I was concerned that it may have quite a bit of wear since it came out of one of GE production plants. It probably had at least 35,000 hours on it. But when I checked the ways I found .001 wear on the home side of the X axis and surprisingly only .0002 on the Y ways. But that is a very reason which is why I bought the Tree mill in the first place. My Tree mill uses a bijur lube system for the XY axis. The quill and spindle use a gear driven pump which makes sure the quill and the spindle gets properly lube. Last I jury rigged three Gecko G320's and set up using 3 80VDc 20A power supplies in parallel to run the 3/4HP 130VDC servo motors. Using Mach2 I can get 96 IPM out of the XYZ axis and probably more after I tune it. I made my first cut with this temporary set up and was impressed with the rigidity of the machine and how nice it ran. Really nice to have a 5 HP spindle motor. I still plan to use the CNC Teknix 200V 40A continuous servo amps but I am having a problem with the PID filter. The program for the I and D needs to be adjusted as I can't get the speed out of the servo amps without them faulting. I also have to use the 12 bit error amp setup in stead of the 8 bit which I prefer. The guys at CNCTEKNIX are going to email me a revised file so I can reprogram the Cypress PSOC chip. In the meantime the Geckos will do just fine. Dan Camtronics Inc I have previously posted that I bought a Tree Mill Journeyman 300 off ebay for $750. I plan to post my experiences in buying such a machine off ebay, having it transported across country and retrofitting the controls in the next few weeks so others can possibly share the knowledge to accomplish a similar project.
October 21,2004 First of all, I have
previously retrofitted a Tree Mill journeyman mill for a customer that has a shop about 20
miles away. I was really impressed with the excellent mechanical condition of his machine
even though it probably had 20,000 hours on it. In view of this and the fact that I was
unable to locate a suitable machine for sale at local machine shops, I turned to Ebay.
Over a period of 6 months I bid on several clean machine with working controls similar or
equal to a Bridgeport series 1 CNC. All of the machine sold for a higher bid that I had
been willing to pay. The one machine that I was the high bidder was below the reserve
price. I had budgeted $5000 for a good machine in good condition with half way decent
controls. Then I saw a Tree Mill Journeyman 300 CNC vertical mill that looked good but it
was being sold as is because parts of the controls were missing. It turns out the cpu and
the crt were gone. I didn't want those anyway so I decided that for $750 and some repair
cost that I could end up with a very rigid machine with modern controls once the retrofit
was accomplish. As I previously mentioned I use "oil eater" to clean
30 years of oil off the machine. The table top looked pristine after it was cleaned. The X
axis had about .001 backlash. The spindle with the Kwik switch 300 holder assembly
was in good shape. The Y axis was probably the reason the machine was sold. The Y axis had
.030 backlash. Disassembly of the Y axis ballscrew assembly reveals that the ball nut
flange was fractured completely just beyond the flange but before the first ball groove.
Since the material is hardened I was pretty sure it could not be welded . I checked around
and found I could buy a new ballscrew and nut for that machine for $1500. Other
replacement ballscrews custom made would also run about $1300. Since the ballscrew and
ball nut were off the machine I chucked up the ballscrew in my lathe and measured
the end play. It was nearly zero!. Then I remembered that really hard material like
carbide is brazed onto tool holder. So I got out my oxy-acetylene torch , removed
the balls and ball nut from the ballscrew. Cleaned the mating surfaces of the flange and
ballnut, fluxed them and the brazed the two ends back together. I reinstalled the balls
and found that it did turn smoothly. When I reinstalled it on the machine and reassembled
the thrust bearings I found the Y axis to be very stiff. So I took it apart again and
found that even thought he races on the thrust bearing looked ok they weren't. So I
replaced the two thrust bearing at a cost of $9.32 each. It now turns very smoothly,
easily and with about .0012 backlash which is
acceptable for my work.
While disassembling the Y axis I noted there was a BEI incremental encoder mounted between the ballscrew and the servo motor. I removed it and tested it. There was no output from channel A, B or the index. I called BEI tech support and relayed what I had found. They asked me how much current it drew. It was 70 MA. They told me that was too low and I would either have to buy a new one for $400 or send it in for repairs and that repairs could cost up to $200 if repairable. After thinking about it for a while I decided that I could easily replace it with a US digital encoder for a lot less. But I wanted to do a few more checks on the BEI encoder. I check quite a few items and then realized that it must be the light source in the encoder. I cut one of the leads and sure enough the encoder light source was open. I assumed it was an IR LED. I removed it and noted that this little light was only .125D and about .187L. I looked at the circuitry and was surprised to see no dropping resistor or the LED. It was wired directly to the +5 terminal and ground. Upon closer examination I could see that there was a portion of a filament inside the miniature bulb. It was an Incandescent Lamp!.
I went through my catalogs and found that Chicago Miniature makes hundreds of different incandescent miniature lamps some of which were 5 volts. I then was able to find that Mouser electronics carried this replacement bulb for $1.60 . I needed to order some other parts for various orders I had so I went ahead and ordered it. When it arrived I installed it and powered it up. I could see the light on and when I connected my scope I could see that all the channels were working properly. These little lamps come with different filaments so you can get them with 10,000 -40,000 hrs of life. Failure analysis of the Y axis was probably caused by the encoder lamp burning out. This most likely caused the Y axis to run uncontrollably into the column causing the Y axis servo amp to burnout, blow the fuse and fractured the ball nut flange.
The spindle motor is a 4.75HP PMDC motor with
tachometer. It is 180VDC and ran off a three phase controller. I didn't want to spend $600
for a rotary phase converter or phase inverter. I bought a KB electronics 5HP DC speed
controller that has a manual speed control or will take a +/- analog signal. It was
pretty easy to install the KB speed controller and tested just fine.
So the only remaining issues is that the spindle uses a bijur positive displacement lube
oil pump to lubricate the up and lower spindle bearings and the quill. The sumps needs
cleaning and fresh lube oil installed. But I need to clean the sump filter before I
install the new oil. I ordered a 3KVA isolation transformer for the power supply (
170VDC ) and have started the retrofit of the controls for the new CNCTeknix servo amps
that I will install. hope to make chips soon.
Dan
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