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Re: Dumb question on the drilling of holes
Marv Frankel wrote:
Jon,Well, there is an optimum feedrate, that varies depending on material and the particular way the end of the cutter is fashioned, that makes for the best cuts. It is the center of the cutter that develops the most force. One trick is to use a smaller cutter first, then follow through with the desired size. I often use end mills to countersink through holes for socket head cap screws, drilling the through hole first, and the results are very good. Aluminum extrusions are generally horrible, plastic alloys, unlike the wrought aluminum that machines well. You may have to use lots of cutting oil, and lift the cutter to clean the flutes with a brush. Harder alloys, like 2024-T6 or 6061-T6 will flow up through the end mill's flutes nicely. But, I avoid machining of extrusions as much as possible. My best formula would be : Drill through with a 1/8" solid carbide end mill, and then orbit the machine to produce the correct size. Use a water-based flood coolant system. When these extrusions get even mildly warm, they plastic-flow and gum up on the cutter, and that is a disaster. Only flood coolant will prevent that. Jon |
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Re: One side gantry drive
Robert Campbell
Doug,
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All of my designs are for moving tables. I have built a gantry machine, but was never able to totally eliminate racking of the gantry. At least I am now aware of what it causes the problem. Bob Campbell ----- Original Message -----
From: "Doug Harrison" <prototype@...> To: <CAD_CAM_EDM_DRO@...> Sent: Wednesday, October 23, 2002 8:04 AM Subject: Re: [CAD_CAM_EDM_DRO] One side gantry drive For the purposes of this discussion I will declare the length of the tablea beam and think of it as a truss (triangle). Think of it as a righttriangle where the long leg is the Y axis and the short leg is the X axis.the X axis trucks is about twice the tool load - not much.without resorting to adding bulk. Les Watts' router base is built this way. It |
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Re: DRO board closer to working but still not
Swapping A & B will reverse the direction, but that is it. Is it bad on all
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axis? What is the environment you are testing in? is it possible you are getting noise on the line? Do your encoders have built in pull-ups or do you have to add some? Lots of the nicer encoders are open collector and need pull-ups. Tim [Denver, CO] I got the board address problem fixed by just installing in another |
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Re: 2 vs 4 flute cutters ( was Re: Dumb question on the drilling of holes
Corey
I've found that 4-flute drill oversize and 2-flute are
dead-nuts accurate. c --- turbulatordude <davemucha@...> wrote: Hi,__________________________________________________ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site |
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Re: DynaCADD ???
mueller914
I use Pro/E for my job and have a license at home as well (floating)
so no CAD program needed or do I really want to learn a new one, LOL I really just wanted the CAM software. Thanks for the feedback though, it's good to know that it is a decent CAD package. Mike --- In CAD_CAM_EDM_DRO@y..., "Mike Snodgrass" <snarf@s...> wrote: I went for the offer and recieved my program a week ago.general cad solution this is a very powerful program for the price! I haveolder versions of Acad,cadkey,gereric cad,dataCad, and others,thisprogram is on par with any of the higher end programs. The CEO of the Co. usedto be the CEO of Autodesk, so go from there. Also is user-friendly. Too badthey are out of business, I am still very satisfied. If you purchase,make sure you get the 3D, Win2000+ program.also mailedlooks like it is only CAD and NOT a CAM package. I politly e- wellthe seller asking that I would like to return it since it is not a wrote:here for this transaction. don'tI have never used it but have seen it on ebay a few times. I hethinkthere are any cam functions in that software and it sounds like reach it ifdoesn'taol://5863:126/rec.crafts.metalworking or go thru Google.com toeven know what CAM software is. I'm not sure he even knows what you have trouble.to be a sister site to the CCED group, as many of the same members arethere, for OT subjects, that are not allowed on the CCED list.POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........bill |
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Re: caudlet Re: Newbie Questions
Lloyd Leung
That sounds interesting, could you post your files to the files section
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to share with us all? Thanks. -----Original Message-----
From: caudlet [mailto:tom@...] Sent: October 23, 2002 7:58 AM To: CAD_CAM_EDM_DRO@... Subject: [CAD_CAM_EDM_DRO] Re: Newbie Questions A couple of years ago, before being donated a full sized mill, I posted a circuit on metalwebnews about how to build a head position sensor with a dual element photoresistor and a laser pointer. It proved to be accurate to about +- .002 of head deflection on a mill drill. Contact me off list and I will try to dig up my old circuit and some pix of the unit. |
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Re: Center tapped transformer
Tim,
You can also connect a full bridge rectifier across the end wires and get the following: 1) +42V and -42V (ground the centertap). 2) +42V and +84V (ground the "-" end of the bridge; the center tap is then +42V). Option (2) is useful if you have a mix of high speed and low speed axies; use the higher voltage for the high speed ones. Mariss --- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote: I have a transformer that is center tapped on the secondary. Voltagefrom one end to the center and get the 30 volts, but it seems like I ammissing out on amperage by not somehow using the other half of the coil. |
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OFF TOPIC Dumb question on the drilling of holes
This discussion on hole drilling is about machining and not about the
subjects of the list, so please drop it. Any questions or arguments direct to me off list. bill List Mom Or take it off list or to: OFF Topic POSTS: General Machining If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list. |
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Motor mount
Marv Frankel
Guys,
For those that I sent the drawing file of Corey Renner's motor mount, I got permission from him to share the photos and drawing of that project. Check them out at: These pictures illustrate a well-designed gearbox utilizing timing belts. If you'd like to see an example of direct drive mounts, try: www.matronics.com/cnc2/ Marv Frankel Los Angeles |
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2 vs 4 flute cutters ( was Re: Dumb question on the drilling of holes
turbulatordude
Hi,
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If I remember correctly, 2 flute are typically on or oversize and 4 flute are always undersize. Dave --- In CAD_CAM_EDM_DRO@y..., "Howard Bailey" <bogmstr@i...> wrote:
Marv, |
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25Khz glitch ? (was Re: Ideas for matching drives on a YY axis design?
turbulatordude
Hi Dean,
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what software ?? Dave --- In CAD_CAM_EDM_DRO@y..., "deanc500" <deanc@v...> wrote:
I have a machine with dual y motors and matching them didnt seem to be |
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Re: One side gantry drive
Doug Harrison
For the purposes of this discussion I will declare the length of the table
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as X and the length of the gantry as Y. To make the single side drive work we must abandon the idea of a gantry as a beam and think of it as a truss (triangle). Think of it as a right triangle where the long leg is the Y axis and the short leg is the X axis. The short leg if the triangle is roughly 50% of the long leg. Thus, for a 60X120 table the distance between trucks that run the X axis rail is about 30-36 inches. As such, the in-plane force (neglecting acceleration) on the X axis trucks is about twice the tool load - not much. The principle advantage of this method lies in the rigidity of the truss. Bending is no longer an issue. Deflection in the XY plane is avoided without resorting to adding bulk. Les Watts' router base is built this way. It seems incredibly stiff though it is only 2X2 box tubing. The one sided approach allows you to invest your ballscrew budget in one good piece instead of two lesser units. The drive side rail should be beefier than the opposite rail. No problem. A disadvantage is that the drive side rail must be about three feet longer than the intended travel - still better than with a moving table though. One of our list members (was it Bob Campbell?) has built a few tables this way and was happy with the results. Doug ----- Original Message -----
From: dakota8833 <dakota8833@...>
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Re: Dumb question on the drilling of holes
Marcus & Eva
Hi Marvin:
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Aluminum extrusion is gummy, shitty material to try to cut. You need excellent chip evacuation and flood cooling to have success. Try a smaller drill to clear the center and then plunge with a boring tool. Unless you have a pretty rigid mill, I wouldn't try plunging with an endmill. Cheers Marcus ----- Original Message -----
From: "Marv Frankel" <dcdziner@...> To: <CAD_CAM_EDM_DRO@...> Sent: Tuesday, October 22, 2002 11:15 PM Subject: Re: [CAD_CAM_EDM_DRO] Dumb question on the drilling of holes Jon,the end mill through an 1/8" wall aluminum extrusion, I could feel resistanceon the quill. Then I realized that, as the cut started, the chips built upend ifaol://5863:126/rec.crafts.metalworking or go thru Google.com to reach itmill, and that wasn't great either.A properly sharpened drill bit will not do this except on very thin you have trouble.OTsister site to the CCED group, as many of the same members are there, for subjects, that are not allowed on the CCED list.DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill |
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Drilling holes (was Re: Dumb question on the drilling of holes
turbulatordude
Hi all,
Thought I'd add my 2 cents here. Drilling holes is probably more than 60-70% of machining, and we all do it all the time. Trouble it that it is so easy we may have started on drilling without getting the basics. As you know, there are 4 common drill lengths, jobbers, taping, screw machine and long drills. In addition, there are specialty drills, center drills and spotting drill fit into that category. Long drill are aircraft or long flute. Aircraft have a long un-ground shank and standard jobbers length flute. Long flute have a flute that is more than half the overall length, often 3/4 or more. Soa 1/8 drill in aircraft might be 12 inches long with a 1 1/8 flute length or in a long flute, it might be 9 inces of flute. The latter is better for chip removal in deep holes or when in use with drill busihings of long length. As was mentioned, common jobbers drills tend to wander as they start a hole. A center punch allows one to locate a hole more precisely. Even a drill press will allow a drill to wander from center as the rotational forces and axial forces interplay. A tight spindle and short drill will greatly reduce this movement. Once a hole is off, it is hard to get back to center without some real work. Drills have two flutes connected by a web in the center. The center web cannot cut, so it just pushes the metal until it can be removed by a flute. When drilling by hand, a center punch allows a small hole to be drilled, removing the center material from the hole. Then the next size drill can do it's work much easier as the material under the web is not there and the energy is in cutting not pushing metal. Here is where a person can make some mistakes. A large drill used to 'clean up' a hole is cutting with very small sections of the bit and can dig into the work easily. We all have experienced the drill getting sucked into the part and the part spinning or the spindle stalling at one time or another. Drilling a 3/4 hole with a 1/4 pilot hole is actually easier than drilling a 3/4 hole in a 11/16 hole. This is easily found when the drill punches thru the metal. The hole naturally opens and the drill may pull in and leave little bits of metal. The drill would actually screw itself in at that point. If using a hand drill the whole thing screws into the part rapidly. When starting a hole by hand, a center punch works well, when starting on flat metal, a center drill offers a small web and a large starter hole. Split point drills offer the best of both. They start cutting in the relief under the web. Spotting drills are split points for that reason. When on a very rough surface or on an angle, it is really hard to get not only a start, but also the get the hole to drill dead center. The reason is that the drill can bend and will follow the path of least resistance. On an angle, the up side of the part will allow the drill to contact and push the drill off axis and the hole will be off center. This can happen on very rough castings or if there are soft and hard spots on the part. How a drill actually cuts is another problem. If the two flutes were perfectly ground, the drill would start, drill, then as the depth of the hole allows the sides of the drill to engage, the drill would seize in the hole ruining the drill. Drill bits must be ground off axis or they will burn themselves up quickly. Most grinders do not have the capability for perfect symmetry, and most people don't have the patience to make that happen anyway. IF you want to try this, grind your drill bit in your drill grinder until it is close, then with little hand pressure just touch up the flutes until there are little or no sparkes. If you put much hand pressure, it will be uneven from flute to flute, so a very delecate touch is needed. A 1/2 drill in a 1" steel plate will work, and remember, no coolant for the test. After the sies of the drill get ruined, try it again with coolant. It will last a little longer, but not much. None of the drill manufacturers list this factet of drill making, or how they incorporate the different angles or different grinds. A drill cuts with the flutes, and the center web holds the flutes in position. If one flute is at a slightly different angle, or if one is ground a little deeper than the other, the angles will evenly contact the bottom of the hole and the drill will bend to allow this. Since one flute is slightly different, one flute will cut the hole a little wider, and the other will cut a little deeper, but not cut the full radius. You can see this on larger holes and of drills sharpened by hand. This allows the inner flute to not rub the wall of the hole, and the outer flute to deflect from the wall and not be forced to rub it. Not knowing this, most of us have experienced drilling a hole with a drill and finding that the hole is oversized. So we use a small drill to get the hole on center and the final hole is closer to the drill size. Then we drill just under and use the final drill to clean up the hole and get closer to size. Also, knowing this, you can grind one flute a little, use a tiny thru hole and get an oversized hole, say for bolt clearance or something. The triangle holes mentioned are from one flute digging in, the shaft bending, then the next flute swinging out of axis and digging in. This is caused by no center support of the drill web and too little material on the flutes to let the drill get centered, and too shallow a hole. You will find this in sheet metal or holes that are shallower than the length of the distance between point and drill side. Using a 132 degree will reduce that distance. Putting a backing plate or sacrificial plate under the part will also help. Also the relief angle will have some part in the hole. Too much clearance and the drill digs too easily. Grind the drill with almost no relief when drilling on thin metals or plastics, or brass and copper. This allows the edge to cut, but also limits the depth of cut. Lastly, when a drill cuts, the drill flute digs into the part and wants to twist. If you allowed the twist to occur the drill would open and the drill might be twice the drill diameter. To counter this, the web holds the flutes in position. As the flutes cut, they spread slightly. The thicker the web, the less the spread, but also the less room for chip removal and the more forces is needed to push the metal under the non-cutting web. This movement is small, but it exists. The duller the drill, the greater force to create this spread, and the more machine force to move the drill thru the metal If you need exact diameter holes, ream. If you need exactly located holes, bore If you need exactly located holes, and speed, spotting drill, then drill as needed. The more rigid the machine the better the locations will be. Machine grind your drills or buy in lot quantities for low prices. If you need located hole, on a budget, make an adapter on your drill press to hold a drill bushing. Then use an XY table to move the part. This is similar to a jig-bore machine and remove sloppy spindles and poor bearings from the equasion. at least on a budgetary scale. Dave --- In CAD_CAM_EDM_DRO@y..., Marv Frankel <dcdziner@p...> wrote: Guys,<snip> ( you're welcome) |
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Re: Center tapped transformer
On Wednesday 23 October 2002 02:55, Tim Goldstein wrote:
I have a transformer that is center tapped on the secondary. Voltage<snip> You want a simple two diode full wave rectifier setup. The center tap becomes ground. Take two diodes and connect the anode end of one diode to each end of the winding; tie the cathodes (bar end) of the diodes together for the positive. Keith Bowers - Thomasville, NC |
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Re: DynaCADD ???
Mike Snodgrass
I went for the offer and recieved my program a week ago.
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As mentioned, there is no cam module included. However, for a general cad solution this is a very powerful program for the price! I have older versions of Acad,cadkey,gereric cad,dataCad, and others,this program is on par with any of the higher end programs. The CEO of the Co. used to be the CEO of Autodesk, so go from there. Also is user-friendly. Too bad they are out of business, I am still very satisfied. If you purchase, make sure you get the 3D, Win2000+ program. ----- Original Message -----
From: "mueller914" <mmueller@...> To: <CAD_CAM_EDM_DRO@...> Sent: Tuesday, October 22, 2002 11:53 PM Subject: [CAD_CAM_EDM_DRO] Re: DynaCADD ??? I did some researching on the 'net...it seems at one time dynacaddaol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill |
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Re: Center tapped transformer
caudlet
--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
I have a transformer that is center tapped on the secondary. Voltagefrom one end to the center and get the 30 volts, but it seems like I ammissing out on amperage by not somehow using the other half of the coil.Tim: Elecronically there is little difference between a full winding, bridge rectifier and a center-tapped dual diode approach. Just connect it up as shown in the ASCII schematic. In most of the switching power supplies the secondary is center tapped and they use a single "half bridge" device (looks like a power transistor)to do the recification. You can find the dual-diode half bridge devices pretty cheap. Look for a common cathode device. The amperage of the secondary is a factor of several things but is usually limited by the size of the core and the size wire in the secondary. Disconnecting the two windings at the center tap and running them in parallel will not increase the amount of current you can get from the secondary. |
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DRO board closer to working but still not
I got the board address problem fixed by just installing in another
computer. There is some kind of input comming in but it is erratic and not working properly. I have tried a couple of encoders and the result is the same. The numbers flicker and jump but don't correspond to any real values. Does having the A and B channels reversed matter? I didn't think so. Any Help Appreciated Joe V. |
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