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Message |
    
fabrica
Registered
Username: Daya
Post Number: 85
Registered: 10-2006
| | Posted on Thursday, November 30, 2006 - 12:09 pm: | 
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These are the first Pictures of the table that I am building. Comment's are most welcome.
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Gerald_D
Registered
Username: Gerald_d
Post Number: 555
Registered: 11-2005
| | Posted on Thursday, November 30, 2006 - 01:34 pm: |
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Hey Fabrica, we need more pictures! 
The little bit I see so far looks okay.
I notice that your welder is using the typical "welder's logic" when working out his sequence - it is not the same sequence as in the drawings. The typical welder's logic is to weld the biggest parts first and then to add the small parts to the big lump. I have learnt over the years that this is not the best way, because it is difficult to turn the big lump over into the correct position to make the best welds. The guys will weld overhead and vertical instead of turning the whole thing over to work with horizontal welds.
The logic in my drawings is the reverse - first weld as many small parts into sub-assemblies as possible. Leave the big assemblies for last. For example, it is much easier to weld the foot onto the leg while you can turn the loose leg with just one hand. |
fabrica
Registered
Username: Daya
Post Number: 88
Registered: 10-2006
| | Posted on Thursday, November 30, 2006 - 06:18 pm: |
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This is what I did initially. Did all markings on the spoil board. Fixed the under supports
(3" x 1.5" U channel)on to the spoilboards. Drilled The perimeter holes on the spoilboard to go through the U channels underneath. Mounted aligned and tag welded the big longitudanal U Channels (6"x3') on to the samller U channels (which were initially fixed on to the spoil board) and turned the the whole thing upside down.
While in this postion I intend to drill 12 mm holes through smaller U channels through the bigger U channels and then run bolts through the holes and grind off all welding tags.
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Gerald_D
Registered
Username: Gerald_d
Post Number: 560
Registered: 11-2005
| | Posted on Thursday, November 30, 2006 - 08:08 pm: |
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Aha, bolted ends! Now you might have discovered another reason for the angle cut on the ends of the 3x1.5" cross supports - to get a drill in there for drilling through the main beams. To get those M12 bolts really tight in future, you should get some taper washers:
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fabrica
Registered
Username: Daya
Post Number: 89
Registered: 10-2006
| | Posted on Friday, December 01, 2006 - 03:28 am: |
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Yes, The angle cuts came in really handy. Other wise getting the holes aligned on the U channels would have been really difficult. Today I will insert the bolts and remove all tags and hope to finish the legs as well.
Where would you need a tapered washer ? |
Manjeet Singh
Registered
Username: Manjeet
Post Number: 4
Registered: 11-2006
| | Posted on Friday, December 01, 2006 - 06:04 am: |
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Why not use guided endmill (Cutter used to make groove for Allen Key Bolts) to dress up the taper U channel and use sipmle wahers instead of tapered washers.
Manjeet |
Gerald_D
Registered
Username: Gerald_d
Post Number: 562
Registered: 11-2005
| | Posted on Friday, December 01, 2006 - 07:07 am: |
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Fabrica, the flanges of your Channel irons are probably taper and the bolts then have to bend....
Manjeet, the guided endmill (counterbore) does not fit inside the channel
Fabrica, you don't have to worry about the taper where the wood table is screwed to the cross-support - those joints are not so tight and those bolts are not highly stressed. Besides, the the taper makes a sort of ratchet action under the nut and that helps to "lock" it.
You might have noticed that the x-rails fit to the main beams with tapped holes - that was to avoid problems with the taper inside the beam. (Beams of that size can often be found with parallel flanges, but that is not essential) |
Manjeet Singh
Registered
Username: Manjeet
Post Number: 5
Registered: 11-2006
| | Posted on Friday, December 01, 2006 - 07:38 am: |
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Gerald,
I had seen the Fabrica table and the bottom supports channels(3x1.5) tagged to the main frame are tapered on both ends so it can be dressed up easilily. But on the main (6x3)U channels only tapered washers is a solution
Manjeet |
fabrica
Registered
Username: Daya
Post Number: 90
Registered: 10-2006
| | Posted on Friday, December 01, 2006 - 09:30 am: |
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I have cut the end's of the cross bearers to accomadate the legs made from 3"x1.5" U Channels. This is to ensure that the Supports, (drawing no 10 10 304 which connects the legs to the cross bearers)cross bearer and legs are aligned on a straight line.
I will be replacing the existing washers with taper washers where it is required.
Cross Bearer with ends trimmed.
Cross Bearer with ends trimmed and foot welded.
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Gerald_D
Registered
Username: Gerald_d
Post Number: 567
Registered: 11-2005
| | Posted on Friday, December 01, 2006 - 11:29 am: |
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The most important drawing for you at this stage is 10 10 300 W.....
Top right corner: Control the Y+430mm dimension tightly. (If it is too big, the racks don't fit - too small and the rails overhang too much)
The other important aspect is to put the table off-center relative to the side beams, by about 100mm. Long explanation on the reason, but you'll have to trust me that it is a good thing to do now.
Enjoy the weekend! I'm off till Sunday. |
Greg Waggy
Registered
Username: Gawnca
Post Number: 121
Registered: 11-2006
| | Posted on Friday, December 01, 2006 - 02:17 pm: |
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Fabrica, It looks like you are off to a healthy start. I'll keep watching your progress. Keep the photos coming as you build, it'll be nice to see the sequences. |
fabrica
Registered
Username: Daya
Post Number: 91
Registered: 10-2006
| | Posted on Friday, December 01, 2006 - 02:35 pm: |
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Thanks for your compliments Greg. It is these encourging remarks which keeps us going.
In places where all six legs are getting mounted the cross bearer has to be trimmed. I hope to complete this work today and do up the cross supports for legs tomorrow. |
Greg Waggy
Registered
Username: Gawnca
Post Number: 122
Registered: 11-2006
| | Posted on Friday, December 01, 2006 - 02:44 pm: |
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I love it when actions are taken. Over on CNCZone there's more talk than action. Oh a few are doing things, but when you consider how many talk and do nothing, it gets old hearing the theory and no practice.
I hope to start my machine sometime this Spring. It isn't fun working outside in the cold.
Keep up the good work!!! |
fabrica
Registered
Username: Daya
Post Number: 103
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 12:34 pm: |
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The under side of the table is almost complete.
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Gerald_D
Registered
Username: Gerald_d
Post Number: 589
Registered: 11-2005
| | Posted on Tuesday, December 05, 2006 - 12:41 pm: |
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One very robust table!
Are you still going to use the bolts, or will you just weld everything together? |
Alan Conolly
Registered
Username: Alan_c
Post Number: 6
Registered: 07-2006
| | Posted on Tuesday, December 05, 2006 - 01:16 pm: |
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Fabrica, nice going, as Gerald said very robust. I see you are building on the floor, how do you avoid building in twist into the frame or are you not worried about that and will just shim the rails until they are all in the same plane?
To avoid problems with uneven floors I have built myself trestles with adjustable tops so that I can get everything in the same plane. Using a laser level makes it all easier.
Currently using them to build roller conveyors but will also come into use when I start on the Mechmate. |
fabrica
Registered
Username: Daya
Post Number: 104
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 01:31 pm: |
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Gerald, Some Joints would be bolted and some would be welded. Everything to be done in such a way that the side weldments could be separated once the cross bars (which are bolted to the Bog C Channel) are removed. This is to ensure that the table could be dismanted and transported if the necessity arises.
Allen the floor is fairly even and we have made the final adjustments by inserting shims between the floor and the table befre we started the final fixing. I will upload more photos in another few hours time. |
fabrica
Registered
Username: Daya
Post Number: 105
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 04:44 pm: |
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The table made to stand on it's feet after all works on the table underside was completed.
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fabrica
Registered
Username: Daya
Post Number: 106
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 04:56 pm: |
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Allen, Thanks for your input. I made the table to stand up on its feet. I checked the table for twisting. It is ok. The two big longitudanal C channels are virtually parallel to each other. The error is around 1 mm end to end. I checked the diagonal distances they are perfect. The toip surfaces of the Diagonal C cahnnels are on the same plane (No errors).
Gerald, When checking parrellel distances fo the two longitudanal beams they are Y+420 and not
Y + 430. I think I have made some mistake somewhere. But I assume this error is within the tolerance levels. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 590
Registered: 11-2005
| | Posted on Tuesday, December 05, 2006 - 05:16 pm: |
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Fabrica, this is the reason I reminded you of the Y+430:
The cross-support should not have reached the edge - there should have a space of 5mm.
Don't worry about that tolerance.
Is all the material underneath C-section? If so, your table should twist quite easily if the top is not completely flat. You can just put some shims under one foot.
If you use tubing (square or round) underneath then it is not so easy to twist the table after welding. |
fabrica
Registered
Username: Daya
Post Number: 107
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 05:24 pm: |
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Yes Gerald you are dead accurate about Where I have gone wrong.
What you have mentioned in the other paragraphs is not clear to me. Can you explain a bit further. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 592
Registered: 11-2005
| | Posted on Tuesday, December 05, 2006 - 05:42 pm: |
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Are parts 10 10 306 and 10 10 312 made of closed box-section or open C-section? C-section twists easily, box section (pipe) does not twist easily.
You don't have any problems, that is a very solid table. However, if you look over the tops of the two rails and they are not parallel then there is a twist and you want to correct it. It is easy to correct with open C-sections because you can just put a piece of thin plywood under one foot and the other 3 feet will still touch the floor.
If you try the plywood spacer with a table made of box-section (pipes) then another foot will also lift off the floor because the table is stiffer. To twist such a table you can screw the feet to the floor and pull it flat. |
fabrica
Registered
Username: Daya
Post Number: 108
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 06:38 pm: |
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Both parts are made from Square box sections having dimensions of 2"x1" and thickness of 3 mm.
The C channels onto which the Rails are going to be mounted have no twist at all and the top is flat. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 594
Registered: 11-2005
| | Posted on Tuesday, December 05, 2006 - 07:15 pm: |
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Fabrica, my eyes are deceiving me....all the pieces look the same size as the legs and cross-supports which are 3"x1.5". They do not look as small as 2"x1"??? Therefore I was assuming you used the same channel everywhere.
If that is 3"x1.5" box section then you win the prize for the strongest table so far! |
fabrica
Registered
Username: Daya
Post Number: 110
Registered: 10-2006
| | Posted on Tuesday, December 05, 2006 - 07:23 pm: |
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Let me re-check again tomorrow morning and conform everything. Too much of dimensional stuff has gone through my mind during the last couple of days. The 3 mm thickenss could be conformed even now. |
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