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  #31  
Old Fri 17 November 2006, 09:38
Gerald_D
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The bed will be moving. The vice is screwed to the bed (as per photo, but will be rotated 90 degrees). So the rail, bed, and vice move as a single unit....over a distance of 36". However, the vice is only about 12"(?) wide, and it will move completely past the cutter position. This is the part that worries me. If the vice was 36" wide then everything will be okay.. In your shaper picture there is a long plate lying in the bottom of the vice. The summary of my comment is that a similar long support will be good under the rail

The chopsaw is good. Don't be concerned about the rail curving after it is cut like this - it is flexible enough to bend back again when the screws hold it permanently in place on the MechMate.
  #32  
Old Fri 17 November 2006, 09:52
fabrica
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I got your point, our assumptions are wrong. The other option is to use the shaper in it's normal cutting direction. If this is so, we could do 24" inch pieces at a time and but join them together. When the rollers start to run on the rail, at the welded joints will it give a jerk to the gantry and spoil the show. If so, how are we to overcome this.
  #33  
Old Fri 17 November 2006, 09:57
Greg Waggy
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What you might do is put a some channel iron under the part you are cutting. Channel down.
  #34  
Old Fri 17 November 2006, 10:08
fabrica
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Greg thanks for your input. Can you please elaborate on what you were trying to suggest to me.
  #35  
Old Fri 17 November 2006, 10:20
Greg Waggy
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Well, where you can get the 36" cut and you are worried about curving, take a length of channel iron or aluminum and place it channel down for your angle iron to rest on. You can make it 4 feet long and that will give you support for 6 inches on either side of your 36" cut.
  #36  
Old Fri 17 November 2006, 10:23
Gerald_D
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Fabrica, I suggest that you test your original plan tomorrow, and see if the drill part works. If that is okay, you can concentrate to solve the vice problem....

Maybe take the vice right off, and put a long solid piece of material in its place. Using your end-mill, cut slightly into this long piece of material to get a nice reference bed. Then clamp/screw the rail to this bed....?

Similar to what Greg said.
  #37  
Old Fri 17 November 2006, 10:26
Brian Backner
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It is possible to accurately mill or grind very long pieces with even a small mill/shaper. You just have to set up an indexing reference:



You first need to bolt, or otherwise clamp, a 1/2" thick steel straightedge along the back of the machine's table and exactly parallel to the longintudinal travel of that table - this is relatively easy to do by using a dial gauge chucked into the spindle.

Then it is a simple matter of setting the rail on the table, first clamping it to the straightedge and then clamping it to the table using step blocks and clamps. Then remove the clamps holding it to the straightedge and mill away with a 90 degree V cutter. Mill or grind 24" or whatever the travel of the table, unclamp, move 23", reclamp, mill/grind and repeat until the entire length is completed.

Depending on the mill/shaper you have, you could mill one entire side of the profile in one shot, or sneak up on the final dimension by gradually lowering the quill. If possible, I'd recommend the former unless you have an accurate Z-height readout or stop.

As accurate as a 12' bed grinder? No, but you should be able to come to within several thou, assuming that your mill is capable of that accuracy.

Brian
  #38  
Old Fri 17 November 2006, 10:29
fabrica
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I will keep your suggestions in mind and have a nother discussion with my machinist and decide on what best to do. In the mean time if anymore ideas come to your mind please let me know.
  #39  
Old Fri 17 November 2006, 10:41
Greg Waggy
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Right now I have a 4 axis controller I need to finish up and test. Then assemble that into my foam cutting machine. The old controller is unipolar and this one is bipolar. The controller I'll use for the new machine will be servo driven and I think I'll just buy the Gecko G320K drivers.
  #40  
Old Fri 17 November 2006, 11:30
Gerald_D
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Fabrica, during supper now I realised that your shaper probably does not have a continuous motor driven sideways movement of that table. I remember that shapers traditionally have a "clicker" (ratchet) drive from the movement of the main cutter slide. When the cutter moves forward, the table stands still, when the cutter slides back a linkage moves the table a little bit.

Your idea of joined rails is not that bad. Realise that you can place the joints so that only one wheel at a time crosses a joint. Only one wheel out of four.

Do you have a friend with a milling machine who owes you a favour?
  #41  
Old Fri 17 November 2006, 12:13
fabrica
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I could invest in a milling machine as a last resort. Tell me what do you have in mind. Allthough I have done a lot of favours to others I expect nothing in return. Maybe as you said my machine has a rachet drive. The machine manufacturer may be using only one main motor to drive all movements in the machine.

Finally I need a perfect machine. Since this is my first experiance with a CNC machine I need it to be a perfect one. I do not want to take too many risks.But still again I would love to to have a machine which has my blood running in it. In the process of building up this machine I would love to contribute some thing to this forum as well.You know what I mean ?
  #42  
Old Fri 17 November 2006, 13:07
Gerald_D
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You are making a lot bigger contribution to this forum than you realise. This forum is full of life and ideas mostly because of your questions. You are my inspiration (slave-driver!) to get all the drawings neatly published and the quantities correct.

A perfect machine is a process, not just a one time event. This is not a machine from a supplier - as you say, it is going to have your blood running it. You can continually modify, tune, improve, as you learn and get used to it.

You really don't need to invest in a milling machine for only producing a MechMate, but all-round it is a better investment than a shaper for general purpose work. Just to make some rails, I am sure that there is someone near you with a milling machine that can help you out. (Maybe your machinist knows somebody?)
  #43  
Old Fri 17 November 2006, 13:42
Greg Waggy
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I know one thing, I'm getting a lot out of this forum. As I start to build I'll take photos and share them with you. If you wanted to have top and bottom "V" rails how would you make sure the rollers hug the rails as tight as needed, springs?
  #44  
Old Fri 17 November 2006, 13:52
Gerald_D
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The spring tension on the motor pinions, against the racks directly under the V-rollers, hug the rollers against the rails on top. In the early days we did get the y-car to jump up off the rails.....when we drove the router into the table before switching it on, and other stupid things like that. Jumping off the rails can be regarded as a "safety valve" .
  #45  
Old Fri 17 November 2006, 15:00
vadeem
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To help stiffen up the rails, how about bolting them to the square tubing before grinding?
  #46  
Old Fri 17 November 2006, 20:54
fabrica
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Thanks For your compliments about my contributions to the forum. Ok assuming that I do get hold of a milling machine owner, what Do you have in mind?.

In this country the hardest part is finding a good milling operator not the investment part.
  #47  
Old Fri 17 November 2006, 21:02
Greg Waggy
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Gerald - Now that makes sense to me.

fabrica - That's why most of us hobby folks do it our selves.
  #48  
Old Fri 17 November 2006, 21:05
Greg Waggy
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vadeem - Just about anything square or channel can be used to stiffen the rail while milling. Just depends on what's available.

This is one great place to toss out ideas!
  #49  
Old Fri 17 November 2006, 21:41
fabrica
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We all waiting Gerald to wake up. Hope we do not have to wait that long. I am eager to get his ideas on a milling operation to do the rails.
  #50  
Old Fri 17 November 2006, 23:19
Gerald_D
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Good morning fabrica. Brian Backner's sketch above explains exactly what to do in a milling maching. You wanted to convert your shaper to a milling machine - I am simply suggesting to go to a real milling machine.
  #51  
Old Sat 18 November 2006, 23:29
vadeem
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I guess what I ment was to bolt the Angle iron onto the C-channel rails, then grind.

I would think that would "stiffen 'em up".
  #52  
Old Thu 23 November 2006, 08:55
fabrica
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Today I started on the V rails.

Below given is the picture of the Jig that I made to mount the Drill on the shaper head. The L iron was clamped directly on the bed of the shaper.

  #53  
Old Thu 23 November 2006, 08:58
fabrica
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Below given are the pictures of the first cutting run that we did with the drill setup. WE intend to achieve the final result after a few more runs since we do not want to overlaod the drill too much.

  #54  
Old Thu 23 November 2006, 09:13
Gerald_D
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Wonderful pictures! That mounting for the drill to the shaper looks professional and it is sign that you are going to succee.(Also the support under the point of the rail). Very impressed with what you (and your machinist of course) are doing!

Just for clarity in the bottom pic....
The regular, coarse marks are the sliced down rail, down to 1". Those are not chopsaw marks....you used the shaper didn't you? The 45 degree bevel is two passes?
  #55  
Old Thu 23 November 2006, 09:35
fabrica
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Gerald, This is a trial run that we did. We are never going to use this rail for our Mechmate. What We had a piece of 2 1/2" X 2 1/2" L iron in our workshop, one side we cut down to around 30 mm by using a flame cutter. Then we used the shaper to give a even height. Then we used the bevel milling cutter mounted on the drill to do the first cut.

We will be learning through our experiences and refining our process further before we do the final rail. Thanks for your compliments Gerald, but the credit should go to my machinist and the engineer. I only motivate them. But they really enjoy what they do. I should be able to upload some more photos tomorrow.

It is a long process. We are targeting to finish off everything within 20 machine hours (around 40 feet of V rails).

You could afford this luxury when you are born in a country where the machinists daily wage is around US 6.00 per 8 hour shift.
  #56  
Old Thu 23 November 2006, 09:41
fabrica
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If I am to reply to the final question in your last post.

Our intention is to first complete the two 45 deg bevel runs initially and do the 1 mm flat area in the final run with a flat end mill. Your comments and suggestions are welcome.
  #57  
Old Thu 23 November 2006, 10:09
Gerald_D
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If you are using an end mill for the 24mm flat height, I suggest you do that first, because it helps to indicate whether the two sides are even (parallel and centered). However, nothing touches that top face, and there is no reason to get it smooth or precise. Because you have the shaper, I suggest you cut all the rails to the 24mm height with the shaper.

Didn't you find that the flame-cut makes a bad distortion?

Our machinists probably get double that wage. Until they start their own companies and then get $200+ per day. (Our big MechMate is currently running 16 hours per day and earning $30/hr - that is a good machinist!)
  #58  
Old Thu 23 November 2006, 11:21
fabrica
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No gerald, you have got me wrong. To get the 24 mm height We are using the shaper. And to flatten out the top to 1 mm width, after the two bevel runs we use the end mill.

On the sample we did flame cutting and encountered the problem that you mentioned. I think I have two options available to overcome this problem.
The first is to make a jig for the chop saw and cut it or else to manually cut it by using hackshaw to around 26 mm heigh and the final cut could be done by using the shaper.
  #59  
Old Thu 23 November 2006, 12:00
Gerald_D
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This is the saw we use:




Ours has another name on it, but it is identical to the photo above.

Normally it works horizontally to cut lengths of steel. (6" pipes max). And it does work surprisingly well. These bandsaws have replaced the old style power-hacksaw in most workshops.





This style can also be used vertically:




The vertcal use is a bit of a gimmick and I have only used it like this to cut the rails. You have to support the saw, otherwise you can push it over in this unbalanced position. It also is uncomfortable for a man to stand in front of it.

But, such a saw is a real asset to a metal workshop because they cut lengths of steel so well (in the horizontal position). Much cleaner, quieter and cheaper on blades than a chopsaw.
  #60  
Old Thu 23 November 2006, 12:24
Greg Waggy
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Geradl, My neighbor has one that is similar to the one sold by Harbor Freight and it does a nice job of cutting. Just about as good as a wood cutting bandsaw does.
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