Hot Tub CnC Machine

Description

This Router Machine can hold a flexible Dremel tool or A Foredom General-Purpose Flex Shaft Rotary Tool - H.44T . This allows for 1/4 inch or 6.25 mm router bits. This machine is fairly symmetrical . Quite a few parts get used in more than one place . Part 16 ,15 and 12 are good examples of how a parts duplicate is used across the machine. . There are lots of less obvious examples as well parts 58 60 36 39 51 52 22 and 4 ., are all redundant parts that get used in multiple places . . I've built 2 Machines like this now and I have the assembly time down to around 15 hours . This is not including printing time just part post processing and assembly . The machine uses a total of six,12 mm rods as linear slides on the x and y axes. I purchased a Befenybay 200mm 4080U Z-axis Screw Linear Actuator for the z axis from amazon. A slight modification was done to this z axes .I took out its adjusting cams and reinstalled them on the front of the z axes slide plate rather then leaving them on the back this allows for much simplified adjustment. I've only attempted that modification on the Foredom flex shaft Mill its not on the Dremel . The stepper motors and the anti-backlash nuts are attached with 150 mm long m3 threaded rods and nuts. The threaded rod goes all the way thru the part and gets double nutted on each end . Most critical parts bolt all the way through as well. To accomplish this I cut the M3 threaded rods from 150 mm long m3 threaded stock to the proper length. Then I saved the cutoffs for parts that required a shorter length threaded rod. Anywhere that I’m not bolting all the way through a part, I'm likely using one of those brass threaded inserts that can get melted into the part. Its with the stepper motors that special care should be taken in taking only one bolt out at a time so as to avoid separating the armature from the rotor this prevents loss of the thrust washer and also introduction of foreign material to the magnetic parts I purchased a cable track Opposite the X and Y axes stepper motors on the 8mm Acme screw is a thrust bearing setup and printed thrust bearing cartridge. This cartridge allows you to set the backlash for that axis. Print Part 31 and 32 with 100 percent fill and sand the face of it a little at a time until you have the desired backlash. Part 31 and 32 are the parts that actually determine the amount of backlash. Part 39 is a bearing race holder. The bearing race is a suitable washer that fits tightly into part 39. With the washer in there, I sanded the part till the washer was shiny and flush with the plastic edge. Part 36 is the inside race holder. It also gets a washer and gets sanded, but it slides onto the acme lead screw and fits tight onto a shaft collar. The set screw on the collar sticks out a little and there is a little notch in the part to accommodate that set screw. See the 7th photo. It shows part 39 on the left side of the picture and two of part 36 facing away from each other on the right side of the photo. There is another part 39 off to the right that can’t be seen because I had to crop the photo to get it below 500 kilobytes. It's these parts 31 or 32 and 36 and 39 that make up the backlash cartridge. They all sandwich together and 4 M3 threaded rods keep everything tight together. If you assemble the end opposite the stepper motor and there is no backlash then you haven’t sanded part 31 or part 32 enough. You can stop sanding it when you assemble it and you can detect a backlash of at least 0.001 inch and not more than 0.003 inch. The face you are going to sand is the face that was up when you printed it. I’m using regular steel m3 nuts and stainless threaded rod so the nut will just crack if you over tighten it. The nut will continue to tighten without a reduction in backlash if its tight enough. Also, any part that holds a bearing race should be sanded so as to not allow plastic to ride on plastic. You want those needle bearings to spin true with low friction. To check the tolerances, part 28 is the backlash/dial indicator tool holder tool. Assembly order is first set backlash at one end, and then install the stepper motor at the other end. Then measure to determine the desired length of 12 mm Rod. , remove the backlash cartridge and stepper motor. Get ready to install the 12 mm rod with bar clamps, and press it into the part. Think ahead and install all necessary parts on the rod. Finally reinstall the backlash cartridge and then stepper motor again after all linear rods are installed. The couplers joining stepper motors to acme screw rods are the two piece type . Originally I used single piece type couplers and the printed parts have little access holes to get an allen wrench thru this works but its much easier to assemble with 2 piece couplers . Parallel bar clamps were used to press the 12 mm rods into their respective parts. (Sixth photo) I'm using LM12utu bushings throughout..Sleeves (Part 27 ,29 and 30) hold the bushings and then the sleeves slide into their respective parts. This makes sanding to a perfect fit a little easier. Its easier to sand the outside of the sleeves then the inside of the holes they slide into. initially the bushings will get stuck. its when the sleves are sanded to the perfect diameter that the 12 mm rods slide smoothly . I recommend first getting the x axes assembled and sliding back and forth by hand then the 2 y axes sides get assembled thru the bushings in the x axes . When it comes time to secure the y axes to the 2o by 2o rails use part 28 again the backlash indicator holder tool to ensure that the y axes rails are parallel this will prevent binding later when the motors ar installed . Slight adjustments can be made simply by tightening the bolts holding the 20 20 rails . The machine should be able to travel from y minimum to y maximum without a change in reading on the runout gauge connected to the end of the x axes drive screw . That is how you know your 2y sides are parallel. I’m using a standard CNC shield. The x and y axis limit switches are double ended. Meaning it trips at the x minimum and x maximum. There is just one switch. However, it is activated at both ends of travel. Likewise with Y axis. They use the typical mechanical limit switches commonly seen on 3d printers. The LEDs on the boards for the limit switches work. I power them with the 3.3 volt supply on the CNC shield and ground. The voltage is always there and if a switch or a wire develops an open, it will trigger an alarm at the CNC shield. 2n2222 transistors invert the limit switch signal. . Here is the switch type I used (10 x Mechanical Endstop Limit Switch End Stop with 22AWG Cable for RAMPS 1.4 3D Print Limit Switch). These switches work well. The design here uses a gentle activation of the switch as travel directions are parallel with switch travel. Placing a piece of trimmed packing tape over the switch lever prevents the lever from accidently getting bent forward in the wrong direction . A little slack in the tape allows for normal movement in the proper direction. When installing a router bit and tightening it down, it's easy to bump the z axis limit switches and bend them. The tape trick solved that problem. I used 2 separate z limit switches . It allows for greater X axis travel distance. Each z limit switch connects to an optical isolator input just like the x and y. The Z axis signals from each optical isolator connect to a diode XNOR gate (Schottky diodes are used here ). The diode XNOR gate output signal connects to a 2n2222 transistor. This inverts the signal and the inverted signal connects to the CNC shield. The limit switches use 3.3 volts. The input to the Arduino uno is 5 volts. Using this specific optical isolator, ( NOYITO 4-Channel Optocoupler Photoelectric Isolator Module Level Voltage Converter Module PLC Signal Converter Module PNP NPN to pnp (3.3V to 5V) again from amazon ) I transition from 3.3 to 5 volts without adversely affecting the operation of the LEDs on the limit switches or on the isolator as well as mitigate stepper motor noise. See the schematic 4th photo. Also, In the firmware I’m running a 350 MS debounce on limit switches. Print 57 is a spring seat for the double the ended limit switch. The springs on the double ended limit switches are the same springs as on the anti-backlash nuts. I just cut them a little shorter to make them fit. Ideal spring length is found by gradually shortening until the valley between the bumps on part 58 is lined up with the bump on the switch lever arm (9th Photo) . A 3 mm threaded rod goes all the way threw part 58 and part 60 screws onto each end of it . Part 20.1 and part 20.2 are stops for the limit switch rod ends on the Y axes only. They contact part 60 on the limit switch You may discover you like part 20.2 more than 20.1 as its shape is improved and guarantees your cable track won't snag it. I have several vacuum parts as no one vacuum part seems to work well with all types of router bits and projects Dremel uses 1/ 8th inch bits and some vacuum apparatuses are designed for 1/8th inch bits. Others are for 1/4th inch bits. Very little vacuum is needed if you are making a pc board. Other vacuum parts are designed for maximum depth and large air flow as you can adjust the machine to cut deep by loosening the bolts in part 42 by sliding the entire z axes lower. Included are 3 types of vacuum attachments .Either of which get glued together and then installed into part 50 or 50.1 or 50.2 . I expect that printing part 50 is no longer necessary as part 50.1 works with both Dremel and Vevor Hanging Flex shaft Mill and part 50 only works with Dremel. However part 50.1 is larger. Part 50.2 is a part that can be printed on a small printer 6 inch or less it works with dremel and flex shaft mill it may be the best yet it also has provisioning for a M5 crank to adjust the vacuum height while the cut is in progress This allows you to cut down in stages or multiple passes raising the vacuum a little with each pass as your cutting tool moves deeper Part 16 has a a few attachments designed to conceal wire and hold cable tracks in the correct position giving things a little more professional look and possibly preventing damage from unwanted vibration. I used 22 awg stranded wire for everything in the cable tracks. each wire is given a number at both ends to assist with identification an then soldered directly to the wires coming out of my stepper motors and limit switches. At the top of the z axes is part 2, a box that secures to the back side of the z axes, its exact position on the back of the z access isn't critical . Its used to wrap up any slack in the wiring so that if I need to resolder a wire , replace a motor or switch I will have the necessary length to service and troubleshoot without running a whole new wire thru the cabling tracks. Likewise, at the other end of the wires below part 21 and 35 there is some room to hide a little slack in the wires for your splicing and troubleshooting needs. I did do my wire splices at the base of the machine first and my wire splices at the top of the machine second.This means the majority of slack is at the far end . There is enough room to run several extra wires in the cable tracks .I ran 4 extra and labeled them on each end . This was planning ahead for lighting and or Lasers .The X and Z limit switches can all share the same power and ground thru the cabling tracks it’s only there switched output that needs to be kept independent. There is only a need for part 46 , 47 and 53 if you Have a Dremel flex shaft . If your going to use a Vevor Flex shaft Mill you don’t need to print them. Instead print 53.1 and a quantity of 2 of 46.1 . Most parts should be prinable on a 6 inch prusa. The Uno/cnc shield shield base (part 24)may be a bit big. The wire guide on the side of it can be eliminated if your print space is limited .That is why you see 2 of them 24.1 and 24.2 . If your printing on a 6 inch bed use 24.2 it will fit and if your running wires right from the cnc shield to the opto isolator board you may not even miss the wire cover on part 24.1. On the z axes each side has part 52 the z axes limit switch holder (makes adjusting the z axes limit switches easier) its held down with m5 bolts about .46 inch long and the limit switches bolt to it with m3 bolts and nuts . the switch has a cover, part 51 . and if you print it in something light colored the LED lights show right threw it pretty well. Same with the optical isolator cover a nice white ASA lets the LED’s shine right threw. But pegt is my preferred plastic for all other parts . This is mostly due to its minimal shrinkage. So far I haven't done a lot with speed control i'm just outputting the router signal from the cnc shield to some solid state relays that sit inside a plastic box with a heat sink and a cooling fan . It works but the shield dose have provisioning for a variable speed control I just haven't explored that in the firmware . I’ve done a dozen carvings in hardwood and 2 in aluminum with this Machine. So far, the machine seems to work excellent. I Have a Torchmate CNC at home in addition to this. This 3d printed machine Is more accurate and better suited for finer detail. Its strong enough to last. Cutting area is 335 by 335 MM (13" by 13"when I back 4mm off the limit switches (a setting in the GRBL firmware). Larger cutting areas are possible with these same components however I think rigidity is an important consideration when it comes to a design that uses plastic . Many small sized machines are a fast print design at the expense of rigidity. This machine design is capable of cutting bigger if I use reference pin holes allowing me to reposition the work piece without compromising rigidity . I have a spoil board on top of the 20 by 20 rails that can be removed . When the machine is complete you can use it to locate and countersink 4 holes in the spoil board for some m 5 bolts to hold it down . M5 bolts hold the 4 corners of the machine to the 2o 2o rails .If these M5 bolts are giving you difficulty remember that you can use M5 studs and install nuts and lock washers on the studs. M 4 Bolts hold down tools and vacuum parts . M3 is used for cable track securing and the anti backlash nuts also pretty much anything not otherwise mentioned . It so far has the accuracy of an inkjet printer and the strength of an arbor press. I’m very pleased with the first projects I’ve completed with it, ..

Statistics

Category

Tags