Rebuilding The Bed

The vast majority of water damage to the machine was to the bed assembly.· For those of you who have the JGRO drawings, I am referring to CNC_DTL01 (Support Motor Side), CNC_DTL02 (Support Bearing Side), CNC_DTL05 (Base Support Structure)and CNC_DTL06 (Bed Support).· The Base support and the end support had absorbed enough moisture to cause a lot of swelling in the MDF.· The Bed support didn't really swell but did sag about 3/8 of an inch.· Needless to say, these would need to be remade.

I kind of struggled with accurate cuts when making the first bed supports.· I was not much of a wood worker then and probably and only marginally better now. Particularly with the little short pieces that went between the long ribs of the bed.· So this iteration I decided that I wanted to do a much better job of making these two assemblies.· After noodling the situation for a bit, I decided to remake these parts in 3/4 inch MDF instead of half inch and instead of making short braces to go between the long ribs, I decided I would do half lap dadoes.· The end result will be a heavier bed but much more rigid bed than what I had made during the initial build.


Rebuilding the Base Support Structure (CNC_DTL05)


dxf-iconI kept all the outside measurements to the original plan. 40.500 inches long by 24.000 inches wide and 3.000 inches tall.· I made the pieces that make up the ribs and cross pieces to half lap with close fitting dadoes.· You can get a better idea by looking at the DXF file for the new part.· You can get it by clicking the DXF Icon to the left of this paragraph.· ·What follows is a pictorial process of these pieces going together.


Bed Base parts ready for assemblyIn this image I have all the parts cut, dadoed and ready to assemble.· The six blocks you see at the bottom of the photo are dadoed at right angles to each other.· I made these to hold the parts together at right angles while the glue set up.· You will get a better idea in the following pictures.


First cross pieceNow the gluing begins.· Here the first cross piece is attached to the three longitudinals with glue.· Here you see the blocks I was talking about in the paragraph above.· They assure the parts are connected at right angles and that the edges are flush with each other.


Second Cross PieceIn this photo, you see that I have attached the second cross piece to the longitudinals.· The idea behind the half lap dadoes is to make the bed assembly much more rigid.


3rd cross pieceHere is the third cross piece being glued to the longitudinals.


The 4th and last cross pieceHere is the fourth and last cross piece being glued into the longitudinals.


1st long side piece2nd long side pieceHere are the long side pieces being glued in.


1st short side piece2nd short side pieceFinally, the short side pieces are glued in to complete the frame.· I have to stop at this point on the frame because I need to get some dowel rod.· I want to add these through the outside joints to help strengthen them.· Also, I want to bolt the top to the frame using barrel nuts.· All said and done, this should be a lot more rigid than the original version of the base support structure.


Bottom Base Frame All Glued UpThe Original Base Support BottomThe image on the left is the completed base support frame.· The image on the right is the original base support frame.· You can see how I used heavier members, 3/4 inch on the new versus 1/2 inch on the original.· Now don't get me wrong, I honestly think that is the machine didn't get wet, I would be using it as I originally made it today.· However, if I have to rebuild I may as well try to improve the original design.· I will show a couple of pictures of the dowels and barrel nuts as soon as I complete them.


Putting in the dowelsIt has been a couple of days since my last post.· Anyway, If you look at this picture you will see that I am adding dowels to all the outside joints.· Although there should be no flexing from side to side or from front to back, I wanted to add these as additional strength to the joint.· I used 1/4 inch diameter by 1-1/4 inch long dowels.· They are drilled about 1/16 deeper than the dowel and the dowels are coated with glue, and a little glue run in the hole and spread with a toothpick.· Then the dowels are driven in to just below the surface of the material.· This way they do not interfere with bolting the front and back uprights to the machine.· The only flex in the assembly now is the ability for it to rack or twist.· That will be resolved when the top is glued down to the framework.· When the top has been glued down, I will install dowels in it as well to give a better joint.


Gluing the top to the bottom frameWith the dowel rods all glued in and dry, I glued to the top to the bottom frame support.· I really wish I had about a dozen or so more of these clamps.· I used all I had.· I have done that a few time.· It just seems like you never have enough of them.· Anyway, I am a little off topic.· When the Base Support Structure is dry, it will be complete and ready for installation when I finish the bed support and end pieces.· When I get to the end pieces, I will discuss the attachments and how to determine the hole spacing for the pipes.


Rebuilding the Bed Support (CNC_DTL06)


dxf-iconJust like the Base Support Structure, I kept the same outside measurements. 40.500 Inches long x 20.000 inches wide x 1.750 inches tall.· I also made this out of 3/4 inch MDF instead of the called for 1/2 inch material.· I scaled the members accordingly.· You can get a DXF drawing of this modification by clicking the DXF Icon to the left of this paragraph.· Again, I made this with half lap dadoes like the Base Support Structure.· What follows is a pictorial of the process.


Material cut outWell, the Bed Support frame is made up of 1 inch by 3/4 inch material.· Here I have them cut out.· I cut a couple of extra in case I goofed up.


Cutting to lengthThe next step was to cut all the pieces to their proper length.· Here I have attached a fence to my miter saw.· When building anything, I found that it is best to take plenty of time for setup.· The nice thing with using this fence is that every cut of a given length is exactly the same as the last.· It sure is an improvement over my freehand cutting skills.


All pieces cut to lengthHere are all the Bed Support frame pieces cut to length.


The dado sledHere I am cutting the dadoes in the frame pieces.· What you see on my table saw is a dado sled.· These are incredibly easy to make and make cutting crosscut dadoes a breeze.· Here you see I have a fence attached with stop blocks.· This way all the pieces that I push through will have the dado cut in the same place as the last.· This is a must if you want the pieces to come together nice and square.· The photo is from the back of the saw by the way.


Dry fitted piecesHere are the pieces all cut to length and dadoed.· They are dry fit together to make sure all went well. Well, from this picture all looks good.· Now to glue them together.


Starting to glue up.Well now comes the glue up.· I will not bore you with so many pictures of the process this time.· I realized after this dried, I added the middle two longitudinal pieces that I could not clamp three then two, that on the next cross piece I had to glue to all five longitudinals.· So I glued them all and weighted it all down.


Bed Support frame all glued up.Dowels installed in the bed support frameI told you that I was not going to drive you crazy with a bunch of photos of the same operations on the bed support frame like I done on the Base Support stuff.· At any rate the frame is all glued together and the dowels rods have been installed.· Next is to glue the top to it.· I will do that when the base support is dry.


Gluing the bed support topFinally the top is being glued down to the bed support frame.· Now that we are near done with this portion of the rebuild I want to admit that my dadoes were not perfect.· Like I said earlier, I am not much of a wood worker.· As a result, the tops of the base support and the bed support are not perfectly fitted to the frame.· There is a little bit of overhang here and there.· Not loads of overhang.· something less than 1/16 of an inch.· Now overhang on the long sides is of no real concern.· But on the short end, well that may or may not matter but I want a good fit for the ends.· I will show you how I plan to correct that when I start assembling the components back together.


Rebuilding the side supports (CNC_DTL01 and CNC_DTL02)


Next on the list are the side supports.· I am rebuilding these with no changes in dimensions to the plans.· I may alter some holes because of the new bottom support and the Bed support but I will cover that when I start the assembly.

Gluing up the side supportsNothing real remarkable here.· I am gluing up the first side support.· Sometimes you just never really have enough clamps.· These were slippery little devils.· Getting things aligned was a pain and I am glad I had William and Zachary, my two oldest sons there to help hold everything in position.


Rebuilding the Gantry Bottom (CNC_DTL18) and the Gantry Front (CNC_DTL20)


Although the Gantry Bottom and Gantry Front are not part of the bed, I put it here because it needed replacing because of the water damage.· Now I need to point out that the Gantry front was in good shape, but when Zachary and I went to remove it, it had stuck to the front of the gantry.· It had stuck so bad that a good amount of the front was left behind stuck to the gantry front when we went to drive it off.


The Gantry Bottom replaced.The gantry bottom was made to the original specifications outlined in the JGRO router plans.· Zachary and I got busy working on it and cut it out, drilled and tapped and installed it before we thought to take a picture.· At any rate, it isn't anything special.· If you have built the JGRO router then you have made this part.


Gantry Front laid out.Here the gantry front has been cut and laid out.· I have finished center punching the holes and it is ready to drill.· I did not drill the holes for the anti-backlash assembly because mine is at a different hole pattern.· I will drill these hole when I do the assembly.


Gantry Front AttachedHere the Gantry front is fitted to the gantry.· The outside bolts are snug, but the center bolt is left loose.· I need to super glue the wooden threads before I actually attach this permanently.· Well, I need to drill the holes for the anti backlash nut as well.


Putting it back together.

After taking all the time to cut the dadoes in the bed pieces for a close fit and gluing them together, I made a mistake.· The bed support had a bow in it after the glue dried when I attached the top.· I had an idea that I thought would fix the problem for me.· I took a piece of 3/4 inch plywood and a piece of two inch angle iron and clamped it all together.· Then put several bolts through it thinking that it would hold the bed straight.· Well it was better, but still had a slight bow to it.· Well, a friend of mine stopped by and we jawed about it a while and came up with another idea to straighten it up.· As you will see in the next paragraph, it worked pretty good.


Putting strap iron on the bed.The bow in the table was downward.· We took a couple of small blocks and set a piece of angle iron on top then used a C-Clamp to pull the bow out of the table.· We used a straight edge and a light to check that the bed was flat.· Once we had the the bed flat we drilled some 1 inch by 1/8 inch strap and bolted it to the side with six bolts.· If you click on the picture you will get a better idea of what I am trying to say.· You can see the angle clamped to the other side of the table and the closer side with the strap iron bolted on.· You can also see that the table is pretty flat.· Small gaps exist because of irregularities in the plywood.


Bed bolted back on the machine.Here the bed support is bolted back onto the machine.  You can see the strap Iron will not interfere with the gantry of the machine.  Now I was left with the decision as to use the plywood as my sacrificial bed, or replace it with something a bit more smooth.  Well, I decided that since I put all those bolts in there I may as well use it as part of the bed structure.  I know this loses more cutting depth, but at least for now that is not a concern for me.  A close look at the picture will show you several of the 20 bolts that are countersunk into the top.


Completed bed rebuild.Here is another shot of the completed bed rebuild less the sacrificial bed top.


Job all done.Last but not least, here is a shot of the complete bed rebuild with the sacrificial board screwed down.


Here is a video of the first cutting after the bed was built but before any real adjustments and before the strap iron was added.  It was cutting this little plaque that showed just how bad the bow was in the bed.




That concludes the bed rebuild. Now, I will look at replacing the stepper motors with better motors and new electronics to run them. Watch that upgrade in another menu link.