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  #1  
Old Sat 27 December 2008, 18:28
gixi
Just call me: Marius (AVO) #32
 
Bucharest
Romania
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Problem with Main Longitudinal Beam

Today I made a test when I discovered a "SMALL" problem with the Main Longitudinal Beam.
IT IS NOT STRAIGHT!
So brute force was necessary... At the end on both ends I measured 255,4mm and in the middle 255mm.
And the cherry on the cake : I didn't leave 5mm extra for the rack
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File Type: jpg Tension2 forum.jpg (110.2 KB, 1311 views)
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  #2  
Old Sat 27 December 2008, 22:49
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
AVO, your choices are:

1. New beams, which may also be bent . . . . . not a good choice

2. Bend your beams in a hydraulic press

3. Bend the beams by welding inside them, at the correct position. For this you will have to explain carefully which direction the beams are bent, so we can shrink the metal in the right place.
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  #3  
Old Sun 28 December 2008, 03:50
isladelobos
Just call me: Ros
 
Canary Islands
Spain
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A good practice for Buy new beams is see the straight whith a Laser Level.

http://www.youtube.com/watch?v=YFQKxGZw_xg
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  #4  
Old Sun 28 December 2008, 04:35
gixi
Just call me: Marius (AVO) #32
 
Bucharest
Romania
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Quote:
Originally Posted by Gerald D View Post

3. Bend the beams by welding inside them, at the correct position. For this you will have to explain carefully which direction the beams are bent, so we can shrink the metal in the right place.
I'll go for option nr.3, but for the moment I have to stop everything because the BIG BOSS will cut my hands off. In 2 days I'm leaving to Holland on a small trip and nothing is prepared...
At the end using force the table is in one piece and it looks like this but the measurements are as I said. You are right, I will check first where is the bend because is not normal to put toghether the table like this even if at the end will come in the right dimension.
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File Type: jpg First test forum.jpg (121.8 KB, 1304 views)
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  #5  
Old Sun 28 December 2008, 12:09
gmessler
Just call me: Greg #15
 
Chicago IL
United States of America
Hello Avo,

Trust Gerald on the welding option.
It worked for me...
http://mechmate.com/forums/showthrea...90&postcount=5
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  #6  
Old Sun 28 December 2008, 14:21
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
...I had a thought.
If you don't feel comfortable with all the above options, you could get 2 new pieces of smaller box tube (2 x 2 ) or so, and add them ON TOP of the existing channel.

This would add to your overall height, but if you build the extended z-slide you will have no issues reaching the spoil board.

Just a thought.

Sean
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  #7  
Old Sun 28 December 2008, 18:28
gixi
Just call me: Marius (AVO) #32
 
Bucharest
Romania
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Quote:
Originally Posted by gmessler View Post
Hello Avo,

Trust Gerald on the welding option.
It worked for me...
http://mechmate.com/forums/showthrea...90&postcount=5
I study the thread and it makes sense. Tomorrow first thing is to check how much the beams are bend and where.
Let me conclude the technique: in area where is the bending I should make some holes and then cut the channel in order to make a gap.
Should I make the holes and cuttings on both sides of the beam?
Thank you for the moment.
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  #8  
Old Sun 28 December 2008, 19:53
gmessler
Just call me: Greg #15
 
Chicago IL
United States of America
Quote:
Originally Posted by Gerald D View Post
AVO, your choices are:

1. New beams, which may also be bent . . . . . not a good choice

2. Bend your beams in a hydraulic press

3. Bend the beams by welding inside them, at the correct position. For this you will have to explain carefully which direction the beams are bent, so we can shrink the metal in the right place.

Avo,

No cutting or drilling is needed.

The holes were in my channel already I just ran a bead of weld from the hole down in order to shrink the metal on that side.

See Gerald's option number 3 above.

Show us a drawing of how your channels are bent.
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  #9  
Old Sun 28 December 2008, 21:27
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
AVO, there is no cutting or drilling needed - only welding

Check for ALL the problems with the beams before we start to weld. Is there bending in the vertical direction? Is there twist? We want to fix all the problems and not make some problems worse with the welding.
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  #10  
Old Sun 25 January 2009, 04:41
gixi
Just call me: Marius (AVO) #32
 
Bucharest
Romania
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Problem solved

I finally solved the problem by borrowing a 10 T press used in car services.
The main beam was bend in several places. Incredible…
Sometimes aluminum profile is better than construction steel. I guess…
It was a hard lesson because I didn’t check the steel and I just presume that everything is OK.
Marius
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File Type: jpg Bending2 m.jpg (104.4 KB, 1168 views)
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  #11  
Old Sun 25 January 2009, 05:18
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I like to see that Marius - good work with the hydraulic pressing!
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  #12  
Old Sun 25 January 2009, 05:23
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Marius,

Cool fix. It makes a big difference. I have a slight bend in mine also.
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  #13  
Old Sun 25 January 2009, 21:14
kanankeban
Just call me: Hector #89
 
Monterrey
Mexico
Do Im understanding right? The bending in the beams makes them not parallel? If so, does it really matters? I thought that the really important parralelism is in the rails. Did I got something wrong?
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  #14  
Old Sun 25 January 2009, 23:04
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Hector, Marius had a problem to fit his gear racks. The beams became too wide at the ends and pushed the gear racks out. (See the first post).
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  #15  
Old Sun 25 January 2009, 23:58
kanankeban
Just call me: Hector #89
 
Monterrey
Mexico
Quote:
Originally Posted by Gerald D View Post
Hector, Marius had a problem to fit his gear racks. The beams became too wide at the ends and pushed the gear racks out. (See the first post).
4mm is to wide? Drilling the holes for the rails more to the outside will solve the problem? I mean leaving tolerance acording to the bending In other words creating a gap enough between the rack and the beam will solve that issue?
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  #16  
Old Mon 26 January 2009, 00:22
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Hector, I believe that he started without that 4 or 5 mm . . . .

Quote:
Originally Posted by gixi View Post
. . . I didn't leave 5mm extra for the rack
And realise that he will have a metric rack 16 or 17mm wide.

If you move the rack outside the edge of the rails, then the gantry will not fit.

So the question actually is whether Marius has constructed his gantry. If he has not cut the gantry tubes 10 20 440 yet, then he could simply move the rails more to the outside and lengthen his gantry.
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  #17  
Old Mon 26 January 2009, 00:50
kanankeban
Just call me: Hector #89
 
Monterrey
Mexico
Quote:
Originally Posted by Gerald D View Post
Hector, I believe that he started without that 4 or 5 mm . . . .



And realise that he will have a metric rack 16 or 17mm wide.

If you move the rack outside the edge of the rails, then the gantry will not fit.

So the question actually is whether Marius has constructed his gantry. If he has not cut the gantry tubes 10 20 440 yet, then he could simply move the rails more to the outside and lengthen his gantry.
Gerald,
Exactly That is what I was asking I havent cut the gantry tubes yet...and I checked squarnes off all members of my table but didnt check parralelism maybe i got some ...tommorow ill check
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  #18  
Old Thu 12 November 2009, 11:32
Claudiu
Just call me: Claus #43
 
Arad
Romania
Need some advise...

Hi guys,

today I was rolling around the gantry seeing that one roller doesn`t touch the rail by the end of the opposite side of the beam where 0,0,0 is.
The distance appears to be about 2-3 mm between rail and roller. The contact is lost 60 cm from the end of the rail towards 0,0,0.
Attachment 7000
I have checked the straightness of the beam and found out that it is bent downward. The bending appears only in the end of the beam like shown in the picture.( Only half of the beam from where I took the pic)
I`ve shimmed it with a 5mm, creating a tension in the beam. The tablefeet seem strong enough to withstand tension and I managed to push the beam upward compensating the gap. I have now full contact with all four rollers on the rail. I even checked and the table is leveled.
What is your proposal for fixing this problem.
1. Should I leave it like this using the big shim (5mm)
2. Should I try to heat up the beam trying to get it in shape? ( and if where is the correct part to put the flame on?)
3. Should i buy a new beam? (which is not a good choice because it`s allready machined on top)
Attachment 6998
Attachment 6999

Thanks for your advice.
Good night.
Attached Images
File Type: jpg oppositezero.jpg (65.3 KB, 770 views)
File Type: jpg oppositezero1.jpg (89.5 KB, 768 views)
File Type: jpg bendingexplained.jpg (191.4 KB, 768 views)
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  #19  
Old Thu 12 November 2009, 14:31
bolingerbe
Just call me: Bryan #54
 
Clinton(Tennessee)
United States of America
Seating the Y Gantry

Claus,

You may want to look at the below link. I help you with your problem

http://www.mechmate.com/forums/showthread.php?t=663
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  #20  
Old Thu 12 November 2009, 16:05
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Claus, You better correct the source, your main beams ONLY !

Stressing them is really not a god thing ! Get to the source first !
You’re not the first with this issue, have a look at this link to help you correct your main beams.
Take note of reading the whole thread...
Amicalement, Robert
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  #21  
Old Fri 13 November 2009, 01:18
Claudiu
Just call me: Claus #43
 
Arad
Romania
Good morning,

Bryan, I`ve already read that solution regarding a twisted gantry. I`ve checked mine but it has definitely no twist. It runs on all four wheels up to the end of the x beam where it looses contact.

Robert, I remembered reading also this thread, it was the first one which came to my head for solving the prob, but my x beam is bowing downwards as I said before, so I still do not know where exactly to put welds for lifting it up...
Which would be the heating technique for bending the beam vertically?

Greetings.

Claus
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  #22  
Old Fri 13 November 2009, 05:23
Claudiu
Just call me: Claus #43
 
Arad
Romania
Hi,

I think about applying heat with a torch to two or three V shaped places.
I also thought about crossing to top of the x beam to get an even shrinkage so I wont get any lateral twist. I hope to lift it upward so the tension created by shimming will be less.
Attachment 7001
Please provide suggestions if you consider another approach.

Thanks a lot.
Claus
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File Type: jpg bended Xbeam.jpg (29.8 KB, 765 views)
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  #23  
Old Fri 13 November 2009, 12:04
Claudiu
Just call me: Claus #43
 
Arad
Romania
Quote:
Originally Posted by Robert M View Post
Claus, You better correct the source, your main beams ONLY !

Stressing them is really not a god thing ! Get to the source first !
You’re not the first with this issue, have a look at this link to help you correct your main beams.
Take note of reading the whole thread...
Amicalement, Robert
Hi Robert,

I`ve read that threat again up to the finish, but I still cannot find the part for bending a beam upward, only read about bending the main beam sideways, or better said straightening it back from bowing in a lateral position.
Maybe I just don`t get it.

Thanks anyway Robert.

I`m still not sure. Is everybody on vacation?
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  #24  
Old Fri 13 November 2009, 13:55
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
This sure feels like a Gerald question to me, and I'm a novice metalworker, but I'll shoot my mouth off anyway:

If you have successfully corrected the problem with your existing 5mm shim, I'd be more inclined to stay with that than to risk twisting your beam while trying to correct it.

My first attempt would have been to apply the shim(s) between the angle-iron rail and the beam, as that would involve fewer stresses built into the machine. You'll certainly end up with some variation relative to the spoil board support channels, but surfacing the spoil board should compensate for that.
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  #25  
Old Sat 14 November 2009, 10:16
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Claus, I understand that Ironman has machined the top of the beams . . . . .

Is that beam straight if you loosen all the screws (did Ironman do a good job) ?

If the answer is "yes", then the problem is created by the screwing down, and then I would say to use the 5mm spacer.

If the answer is "no", then you can bend the beam to fix Ironman's error. A flame alone will change nothing. The easiest is to use some extra welding. I will look for the thread where I think I explained the welding method . . . .

(Also, do not forget that it is perfectly normal to place some shims/spacers between the rail and the beam to get the final straight line of the rail.)
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  #26  
Old Sat 14 November 2009, 15:37
Claudiu
Just call me: Claus #43
 
Arad
Romania
Hello Gerald,

To answer your question, it is yes and no

yes, the ironman did work the top surface after welding on one 6mm plate which he grounded down to be even.
But...as he fixed the bent beam on his machine, he forced it into position.
After finishing his job he released it and it came back to it`s banana position.
So in fact his job was done ...

I disassembled the two main beams, put them one besides another.
Result is that one is perfectly straight, (checked with thin steel wire) and the one we`re talking about has a bent down 4 mm. ( in this case I put some sawhorses at one end and at about the middle of the beams.

I also checked the table legs with that thin wire and they are even.

Conclusion is: It`s the main beam !

Gerald this link refers to bowed beams but I think the weldings have to be put in an other manner to have results for this particular vertical problem.

May be it`s possible to get it straight half by shimming the beam and half by fine tuning (shimming) the rail?

To be honest I`m not such a good welder to start straightening beams by heat...but I`ll try if you think that`s the way to go.

Thanks much for helping out

Good night
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  #27  
Old Sat 14 November 2009, 22:21
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Remove the bent beam and put it upside down on your good beam. It should be a little like a rocking horse with its weight carried in the middle. Put 5mm spacers between the two beams, in the middle and 3mm spacers nearer the ends then clamp the two beams together at the points. (You will not damage the good beam)

Then make 30mm long welds (at a high current), at 400mm intervals:

Remove the clamps, turn the beam over and check it again for straightness. But, also check if the welding has caused a bend in the horizontal direction. Tell us the results and then we can decide what to do next.

(If Ironman welded a strip on the beams, those beams were very bent after their welding (20 to 40 mm?). They must have had a method of straightening the beams before machining. They should be able to offer that method again)
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  #28  
Old Tue 17 November 2009, 04:54
KenC
Just call me: Ken
 
Klang
Malaysia
Hi Claus,
2mm is good tolerance for structural fabrication. IMHO it is better to leave it as it is and level up the angle rail with shims, Garald designed the multiple bolt along the beam for this purpose. Straightening your beam will be too much work... for the matter of fact, it is actually impossible to straighten your flange side bow without introducing wedge side bow.
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  #29  
Old Tue 17 November 2009, 06:44
gixi
Just call me: Marius (AVO) #32
 
Bucharest
Romania
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Hi Claudiu,
Nice work till now. I told you at the phone that will happen. I had the same problem but as you see from those pictures the beam was bended in other direction. I put some heat on it and then the beam was forced to stay in position. I didn't use to much heat because you can't control this process in a matter of mm. Ok Gerald build this machine with many tolerances but don't abuse because 2mm there + 1mm in other place it will became soon a nightmare. Take me for example when I have to refinish the X rail. Do the right thing when it's still easy. Call me if you have time or as I told you on the phone come to Bucharest to see and discuss what went wrong during my construction.
Bafta si spor la treaba !
Marius
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  #30  
Old Thu 19 November 2009, 09:25
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Claus, are you still thinking of what to do? I am curious if will consider the weld method and give us some feedback.
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