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  #61  
Old Sat 03 April 2010, 14:56
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Ron- Jim gave me a good lead for a 1000lb capacity table lift at Harbor Freight for $199. There's one in town, so I can wait for a possible sale to go on to pick it up at that time.

I realize that the one I had pictured with the air hydraulics could pose a problem if it traveled too far. It would definitely damage the machine and getting into limit switches will be complicating things further. I had the same scenario when my first design was to use a motor to drive the sprockets. I saw the potential of the motor going to far without a sought of electronic control to stop it, that's why I later opted for a manual hand wheel.

I'll look into ebay with your suggestions. Starting to see a much simpler solution to this. Thanks-David
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  #62  
Old Sat 03 April 2010, 17:36
JLFIN
Just call me: Jim
 
glenwood iowa
United States of America
i think if you raise slightly past holes on this design you can pick holes off on the way back down ( one at a time )
and Dave I agree with double size as per harbor freight specs I just didn't know what the beastly table would weigh in at

Last edited by JLFIN; Sat 03 April 2010 at 17:39..
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  #63  
Old Sat 03 April 2010, 20:09
KenC
Just call me: Ken
 
Klang
Malaysia
Quote:
Originally Posted by Temuba View Post
The taller gantry will not work also, I already covered that limitation due to the 7'4" ceiling height in my SMALL, did I mention SMALL, shop. As drawn with the 22" z the setup is at almost 7' from floor to top of up most z travel.

David
You looked too far outside of the box

Look closer at 1020456 & 1020251.
Extend 1020456 by 1' while keeping the mounting hole location relative to the rail as original.
Make 1020251 larger but keep the motor mounting holes relative to the V-wheels same as original
If you think the overall height of the machine is too much, you can increase the gantry height by 1' ft & lower the bed by 1' or which ever ratio that is convinient to you.

BTW, is your shop a container box? the dimension sure do look like one.

This is definately do-able, more economical, meets your needs & still keep the distinct MM identity. Most importantly, fail safe.

Wish I can model the drawings as fast as you could....
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  #64  
Old Sun 04 April 2010, 22:02
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Table: Adjustable/Lift Design-Version 4

Here's another crack at it based on some of the recommendations of some of you guys. The most effective, simplest and economical design is using a scissor lift table. The one so far chosen is the one on post #61. I didn't draw the scissor lift because I don't have it in front of me for detailed measurements. However it will be somehow attached directly underneath or within the table.

Also now changed to the previous design are four THK SR20 linear rails. These will replace the thread assembly to better guide and keep the table in alignment with the static base.

The details are not final, they will greatly depend on once I start purchasing parts and steel. At that point I will have to possibly reverse-engineer certain components and details to suite the parts at hand. At least the drawings will give me an idea of what I need to buy and how to go about the build.
Thanks-David



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  #65  
Old Mon 05 April 2010, 21:58
cab. guy
Just call me: Ron
 
Boise,Id.
United States of America
Dave,
Go back to your 1st design,look at the difference in weight on the moving table.The last design is not only overly designed, but puts all that weight in the worst possible place on the top---top heavy.Wheres the foundation to keep those rails properly
adjusted at both elevations?Think about keeping 60 -65% in the frame were it belongs.Consider a sub box frame that would cradle a table landed.A strong sub box frame is key to your design concept.The table itself can be rather simple,using rectangular tubing.Choosing the right size steel and wall thickness,It can be a flat
rectangle weldment. As for as center deflection goes,if its not to your own satisfaction add a couple of 5/8 tie rods along the beams for adjustments.
On a side note the sr are designed for vertical travel.The shs,hsr at the same price,
handle multi-directional loads.Excellent design work.
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  #66  
Old Tue 06 April 2010, 09:49
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Ron- I'm trying to absorb your opinions here, so please bear with me, thnaks. Are you referring to the first sketch in post#1?

As far as, "Wheres the foundation to keep those rails properly adjusted at both elevations?". Do you mean how they tie in to the side base? If so, the linear rail blocks are attached via a bracket to the horizontal L3x3x.5, which is then attached/connected to the side base. All these points are stationary while the table and linear guide rails move up and down.

The weight issue of the table you mention: Basically reduce the steel/weight of the c-channel sub-assembly to something similar to the 1" steel tube in the truss system below it?

I didn't mention it before but the reason for the c-channel is so I can have access to screwing the MDF from below. That way I wouldn't have any exposed screw head at the top of the MF board as I plane the board down over continuos use. Insted of the C3 c-channel, I can get a smaller profile like a C2. Basically 2" tall by 1" wide c-channel. You have a good point since the larger C3 will not improve the rigidity of the table any more than the C2. This change to the steel may reduce the weight at that point about 30-40%.

As far as the vertical C3 you see in the last design: First I need that size for the bolt plate guides to accept the bolts, washers and nuts. However I can reduce the ones that the linear guide rails are on to the smaller C2 c-channel size.

"if its not to your own satisfaction add a couple of 5/8 tie rods along the beams for adjustments." Can you please clarify or markup on one of my sketches?

So they SR I spec are good, right?

Thanks for everything Ron, great help.-David
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  #67  
Old Tue 06 April 2010, 10:12
melissa
Just call me: Melissa #83
 
Brighton (Ontario)
Canada
A simpler option?

I don't know if anyone has mentioned this in this thread yet... have you had a look at what Greg did for his mechmate #19?

http://www.mechmate.com/forums/showt...9&postcount=34

Michel
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  #68  
Old Tue 06 April 2010, 14:37
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Table: Adjustable/Lift Design-Version 5

Ron- Let me know if I followed you correctly based on Post #66 I wrote above. Still need some clarification on the last line. -David


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  #69  
Old Tue 06 April 2010, 14:41
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Quote:
Originally Posted by michelg View Post
I don't know if anyone has mentioned this in this thread yet... have you had a look at what Greg did for his mechmate #19?

http://www.mechmate.com/forums/showt...9&postcount=34

Michel
Yes, the idea is very similar to mine with the deep Z axis. However, he only built for a deep axis and not for a possible indexer that would require the table (or cavity) to be deeper. At least what I would like my specs to be.

Thanks, it's difficult for me to read every build done so far, I missed that one. Very interesting.-David
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  #70  
Old Tue 06 April 2010, 20:11
cab. guy
Just call me: Ron
 
Boise,Id.
United States of America
Dave,
Greg's pictures are exactly what I'm suggesting.The table itself,A simple flat platform,that goes up and down.The foundation that I'm referring to is also just like Greg's,note the stiff box welded frame.The box bottom helps to keep the outer posts
plumb and unified.Yes, this in principal is very similar to what I was suggesting.
I didn't know that this design existed,but cheers to Greg.I don't know that Greg ever
actually changed elevations (stage 2).Imagine in principle this same design with,
A.much larger rec steel for the table.
B.a centered mount scissor jack
c.adjustable linear guides.
D.mechanical stops top and bottom.
E. Incorporating a 4th axis that has yet to be discussed.

From you it would be helpful to know on a 100 x53 cut table, what is the distance between guides?How long are the guides?Is the distance between guides based on a prefab gantry or is this adjustable?
Tie rods if needed ,run length wise to the table platform.They can remove deflection in the table (sag).
If you contact Art in Texas,He should be able to give you valuable advise on that tall gantry.
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  #71  
Old Tue 06 April 2010, 20:16
cab. guy
Just call me: Ron
 
Boise,Id.
United States of America
Sr s should be fine .The rails can be cut .
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  #72  
Old Wed 07 April 2010, 20:02
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Table: Adjustable/Lift Design-Version 6

Ron- After carefully studying Greg's build, I understand your comments now. I've made some major changes from the previous sketch loosely based on the original one posted in the beginning.

1-You will notice the additional two cross members (1.5"x3" tube) in the center that tie both side bases together.
2-Linear guide rails and bolt guide rails are now attached to the side base, and the linear truck/block and bolt block are now attached to the table.
3-The table was changed back to the original C4 c-channel.
4-The hydraulic scissor table has been added with two C4 c-channels running alone the y-axis welded to the two longer x-axis C4 c-channel of the table. The scissor table is represented by the lower box (base unit) and the upper smaller box (moving part of the scissor table top).

As far as Greg's build, I didn't see mechanically how the table would be lifted or adjusted to the next higher level. No holes, steel, nothing. I'm thinking he might just place a large spacer between the cross members and the table to get the correct height and then either bolt or clamp in place. Great concept and design.

Indexer is another story, the empty or non-cutting area toward the rear will be dedicated for the indexer. The other business end will be bolted to the table and slide alone the x-axis depending on the length of the project.

Thanks for the inputs-David





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  #73  
Old Wed 07 April 2010, 20:25
KenC
Just call me: Ken
 
Klang
Malaysia
If you could run a finite element analysis on your structure to check for deflection under load.
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  #74  
Old Wed 07 April 2010, 20:39
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Quote:
Originally Posted by KenC View Post
If you could run a finite element analysis on your structure to check for deflection under load.
Ken-you're going to have to step into this question above. I have no means of figuring this out. Most of my work/design here has been purely based on mechanical drawings using Sketchup and a lot of know-how. I do have access to Solidwork and understand it will analyse various criterias but I am not fluent in using the program.

If you wish to give advice or guidance, I am always willing to learn something new. If not for just the enjoyment of experiencing it once. Thanks-David.
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  #75  
Old Wed 07 April 2010, 21:09
KenC
Just call me: Ken
 
Klang
Malaysia
I'm no guru, giving advice or guidence way over stated., discuss is more appropriate.
I mention the simulation because at the first glance, your latest structural rigidity bothers me & I could be wrong too. Also, just by saying "its not rigid enough" isn't going to help, so some numbers would be unbias.
I'm not familiar with Solidwork, but Acad, will see if I have time to run a simulation.
I too enjoy experiencing everything once
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  #76  
Old Wed 07 April 2010, 21:18
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Ken- I have a friend who has Autocad 2010 in his office. I may be able to borrow a copy for personal use only (like this). Is it the same as yours by Autodesk. I am (or was) very fluent in Autocad. Is it possible to maybe get a few ideas on how to make this happen on my end so I can get an analysis? You now have my curiosity.
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  #77  
Old Wed 07 April 2010, 21:49
cab. guy
Just call me: Ron
 
Boise,Id.
United States of America
Dave good job,
Yes , this is very similar to what I was trying to describe.A modified thought was rather than leaving the tops of the vertical rails floating,bolt it on to a adjustable
bracket for fine tuning,at which time,with some confidence it can be pend top and bottom.Diagram #2 shows the table at the top floor,Here's where you can use horse shoe style shim and through bolt table to rails to help solidify the table to frame
in addition to stabilizing X axis rails.I think you will find the jack will weld into the base table just fine.If you decide to forgo the shim idea, then use thk 25shs on the vertical guides.I'm not sure that Greg ever changed elevations.It appeared that he was going to attempt to do so in a manual fashion.With regards to the jack, You might also consider a ball-bearing plate under the table,driven by the jack.
There's a lot of bolts shown here,how about the welding?
If you can get those measurements, I can help with a steel schedule.
Your looking good.
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  #78  
Old Thu 08 April 2010, 08:15
Temuba
Just call me: Dave
 
Vineland,NJ
United States of America
Ron- In the previous post I omitted certain details off the sketches and description. As a new note I increased the previous C3x4.1 c-channel to C5x6.7 c-channel to have two purposes, see image 3.

1-The THK linear rail guides will be attached to the vertical C5x6.7 c-channel.

2-The THK linear guide blocks/trucks and bolt plate blocks will be attached to the table itself. The bolt plate block will have horizontal movement in the y-axis via two bolts. This will allow fine tuning to fit snug up against the bolt plate guides at the base.

I believe that no matter how careful I am with layout and measurements and decide to weld these, they will never be perfectly parallel to the opposite side, as the table moves up and down. By just loosening the top bolts the bolt plate blocks will have some play horizontally as the table is raised or lowered via the scissor lift and linear guide rails. Once the table position has been determined, two side bolts can be inserted and bolted to the side base and then the top two bolts can then re-tighten to remove the horizontal play from the table.

3-Also notice in the third image, that with the table at the top position the bolt plate blocks are directly below the TS5x2 tube steel (X rail beam). I believe that the table will be in this position the majority of the time. I hope I understood your comment (Diagram #2 shows the table at the top floor,Here's where you can use horse shoe style shim and through bolt table to rails to help solidify the table to frame), and this clarifies that. In your opinion, do you still think that the THK 20mm will work or should it be increased to 25mm?

My only concern is that in this latest sketch, I omitted the diagonals in the side bases. As you mentioned about welds, everything is welded except where you see bolts/bolt plates. I need to be able to disassemble this machine if I build it in my basement and decide later to move.

KenC is seeing into a deflection analysis or maybe guiding me somewhat to do it myself. As far as your comment regarding a steel schedule, do you mean a list of materials for this part? If so, I have that under control and familiar with the various steel sections and weights. If I'm wrong with your comment, please advise.

My decision to remove the diagonals is because the side base will be completely welded and there are plenty of heavy vertical steel members within. However I am not sure if this is somewhat true considering the heavy C5 channels I updated to the side bases. Some of the measurements in the table are not final and I cannot input them until I purchase the scissor table and the THK linear guides. At that point I will have to reverse-engineer some of the details and measurements based on detailed measurements of these two items.

Again thanks to you and the others for the great information and help. This part has not only been a design challenge for me but very enjoyable discussion here.





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  #79  
Old Thu 08 April 2010, 19:53
TheDave
Just call me: dave
 
Toledo (Ohio)
United States of America
Just a thought

Your table is looking good! I just had a thought.

You are going to spend a lot of time coping both ends of those c-channels to fit into your table sides (red circle). Why not invert the channel so you can just butt them together?

Please excuse my amazingly crude drawing.

As I said, it's just a thought. I totally understand if you want to leave it as is for aesthetic reasons.
Attached Images
File Type: jpg thought.JPG (41.2 KB, 550 views)
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  #80  
Old Thu 08 April 2010, 20:46
KenC
Just call me: Ken
 
Klang
Malaysia
Its been a long while since I last did any FEA, there are many free software out in the net, have a look at here
I am not recommanding any particular software as there are far more choices then when I need/have to do such analysis.

Last edited by KenC; Thu 08 April 2010 at 20:50..
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  #81  
Old Thu 08 April 2010, 21:40
cab. guy
Just call me: Ron
 
Boise,Id.
United States of America
Dave,
Using brackets in lieu of shims will work fine.If you limit the amount of attachments
may work better for you, corners and maybe ctr. posts only,let the rest float.Caution on vertical holes,they should be dead on.Remember each elevation change requires
a resurfacing process that should be minimal skimming.You could drill those holes accurately by drilling them after the fact using the Z axis to define elevation.The Z axis is the reference. The linear
guides are as I pictured also.If you mount them on separate adjustable risers, you will be able to tune them.Their needs are not just parallel but on plane as well.If you raise the table leaving the rails loose the trucks will show you where to tightened
the riser brackets.The explanation is oversimplified but in principle is correct,the alternative to this is less than exciting.I believe that somewhere you commented on
using c-channel on the table ,because it was easy to through bolt to.On my machine
I have +/- 300 drilled and tapped holes,in1/4 -3/8 walled rec tubing.The average
time to tap a hole about 90 seconds with a cordless drill--kind of a non issue.Unlike the rest of the world ,here in the US rectangular tubing is bountiful.Here's where you might want to do some more research.
Dave, the welding is for any part of the machine that does not need adjustment,Think about the jack hammer effect.Provided that you tie the moving
table to frame base 20mm is no problem.In other words don't rely only on the linear
rails as a form of attachment.

Anything taken away from the steel will retard performance.
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  #82  
Old Thu 08 April 2010, 22:09
KenC
Just call me: Ken
 
Klang
Malaysia
This build is going to be very complex & demanding with no promises. There are too many alignment for a structure IMHO...
1) hole location,
2) linear slide line & plane alignment. & there are so many of them... we are looking at 0.05" to overload the slide...
worst of all, I can not find a reliable datumn to work from...

My original suggestion was for a scissor lift as prime mover, some rod in pipe guide as very primative guide to ensure the bed doesn't run freely & using locating pins to locate hole accurate enough & secure with bolt through to secure & strengthten.

For the locating holes, you don't want/need to drill in situ, drill a set of precision holes on a separate plate, then mount them on while you are alignming the bed.

IMHO, it will be near impossible to achieve your kind of objectives with fabricated steel structure w/o precision jigs which will cost as much as your whole steel consignment. & very difficult to carryout in your 7' headroom workshop.

The more I look at it, I am more inclined toward JLFin's suggestion of a removable sub base on a fixed bed. Since you have space limitation, why not a small fold away sub base which you can stow away under the bed.? eg, a few boxes at for handling by one person build to precise height. Looks really crued but guarantee to work.

I'm considering this with the overll picture that you are building this for your business use, hence, money & time are important.

Last edited by KenC; Thu 08 April 2010 at 22:23..
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  #83  
Old Fri 09 April 2010, 21:37
Red_boards
Just call me: Red #91
 
Melbourne
Australia
I don't know much, but from experience of my many "shortcuts" over the years it's pretty difficult to lift something horizontally and then line up bolt holes. I've found that lifting at an incline and locating holes at one end, then doing the same at the other and locating the holes, the "filling in" between can be easier.
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  #84  
Old Sun 22 August 2010, 01:46
chunkychips
Just call me: nick
 
Melbourne
Australia
Not sure if you all came up with the ultimate solution already but I have a suggestion that is relatively low tech which might work. This may be what Ken was talking about above but anyway here goes...

How about creating one or more torsion box platforms out of light mdf. These would be the same dimension as your base support board and could be bolted directly to it to provide a raised platform. You could store them under the table when you want to work on thicker stuff.

There are plenty of places online showing how to make a torsion box and if you use the MM to make the ribs it would be very accurate. If you then surface it it should remain flat and true (in theory).

You could make thinner ones and stack them to give you some flexible height options.

Of course I could be way off the mark

Here is a sketch of what I mean (in xray view). I have left the ribs exposed around the perimeter to facilitate bolting and as a bonus you can use the lip to clamp work or a spoiler board...
Attached Images
File Type: png torsionbox.png (75.0 KB, 322 views)
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  #85  
Old Sun 22 August 2010, 14:08
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
...in the Theatrical world we call those stress skin platforms - and they work very well.
A good affordable solution for adjustable table height.

Sean

Last edited by smreish; Sun 22 August 2010 at 14:11..
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