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Thread: Large router table capable of being dismantled and fit through a standard doorway

  1. #13
    Member peteeng's Avatar
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    Default Re: Large router table capable of being dismantled and fit through a standard doorway

    Hi Dan - Here's a shot of some magic tig brazing. Much better then I ever did. Its a motorcycle steering head in CrMo tubing. Some years ago I was involved in a bicycle frame project selling into europe and we had to met European fatigue rules. The TIG steel frames could not met the cycles and load required, the brazed steel frames did. The aluminium tig frames just did and the carbon fibre frames we could not fail. If you do an image search for tig brazing there's quite a bit out there and there are videos as well. Peter

    Hi David and others - The issue of connections is an interesting one. If you decide to bolt you need flanges or thick material. Both take up real estate in your design and need access for spanners. If you weld you need to deal with the fit's and the distortion. You can't use chewing gum yet but maybe down the track. If you use adhesives you still need a flange or you may try fillets but still need some room, same room as a bolt I'd expect. Welding/brazing/hard solder/soft solder allow you to butt join objects. No real estate required just the thickness of the material. This is the attraction of these methods. For a router the connections need to be as stiff as their mating components to maintain structural intent. I suspect that soft solders (like used for soldering wires) maybe OK David to have a play with. These melt at 200-300deg C so the metal does not even change colour. Your frypan gets to 250deg to cook an egg...A simple propane torch and good cleanliness and flux will get you there with the sort of thicknesses you are talking about. Looking at the table attached the mid range solders are 50MPa strength which is quite good in a large surface. The silver solders are near 100Mpa. Take a 50x50x2mm square tube it would take over 980kgf, a tonne to pull it apart which is unlikely to be seen in the router. If it was a column say or at the end of a gantry. If you used 100x100 tube SHS it would be 2 tonnes etc. This is also easy to pull apart if you needed to. Definitely would not distort as far as this router is concerned. I'll have a play next time I get the torch out... keep Making

    Attached Thumbnails Attached Thumbnails Large router table capable of being dismantled and fit through a standard doorway-tig-braze-jpg   Large router table capable of being dismantled and fit through a standard doorway-solder-jpg  
    Last edited by peteeng; 03-19-2019 at 02:57 AM.


  2. #14
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    Default Re: Large router table capable of being dismantled and fit through a standard doorway

    Hi Dave from another Dave;

    A few clarifications.

    First; with respect to extrusions there seems to be this idea that they are perfectly straight and flat structural materials. They aren’t but often are good enough for a router in question. Some extrusion vendors, such as Misumi, actually offer grinding services to better flattentheir extrusions for CNC usage.

    Second; steel tubing comes from a variety and of manufactures, some with much tighter controls on dimensions and flatness. So how much remediation is required varies considerably. Sometimes surface cupping can be dealt with buy cold rolled steel flats bounded with an epoxy filler. This isn’t leveling per say by rather just a way to deal with a cupped surface on square tubing that isn’t flat. The point here is that there are many ways to deal with the problem of less than perfect steel tubing.

    Third; what I was trying to get at is that the brackets you imagined holding up that extrusion will be very difficult to get exactly in line acroos two different frames. The thought was the combination of jack screws and epoxy grouting at the pads (brackets) may be needed or at least helpful in alignment after a move and set up. Actually you likely could get by without the grout.

    Forth; the idea of making the machine deferrently that is a full sized table and separate leg frames or cola psi level legs may be a better approach. If the table can be kept as one piece a lot of your mechanical issues go away. Thus the mention of a built in method of attaching wheels and the ability to turn the table on its side for transport. This of course will only work if an 8’ long table can negotiate all the turns involved. In any event the idea here is to avoid the mechanical issues trying to join two tables together will produce.

    Fifth; This might be obvious but steel frames get heavy fast. I learned this from piecing a steel bench together from an old machine frame. Every time I welded something on it the thing got heavier, imagine that!!! In any event weight is an issue with any machine designed to be transportable. So put emphasis on weight projections during your design and ways to handle the weight.

    Sixth; Extreme precision for the entire table top frame may not be a good investment in effort. The only thing that needs to be precise are the mechanical motion components. What is inbetween isnt as demsnding, that is a spoil board or a subboard for the spoil board down need to be precisely aligned with the axis. The common practice is to mount such boards and then flatten them with the machine. The better the alignment the less waste of course. So what you need is to have the two outside frame members in plane, this is where a lot of people use epoxy leveling, not so much for “level” but rather to obtain a flat surface that is one plane to mount linear rails to.

    Seven; one critical aspect to limit distortion in welding is to precisely fit up parts. That combined with a flat surface to mount the components to prior to welding is very helpful. Of course you run into a problem of access to tooling but it is common in the automation industry to machine steel tubing to length and squareness in a horizontal mill. The better the parts fit before welding the less built in stress you will have and you will get reduced distortion.

    In any event I’m hoping this clarifies things a bit. There are likely dozens of ways to solve this transportability issue. You just need to figure out what makes sense for you.

    A little P.S. here;

    Someone mentioned above the use of adhesives above. This might not be a bad idea, if you have every dealt with shafting assembled with Loctite you will understand how well this stuff holds. Today there are many more options that the traditional loctite bonders. The problem as I see it is the need to manufacture close fitting brackets and the like (sort of like joist hangers) to glue everything together with. This makes me wonder if anybody is actually manufacturing such brackets in volume, I’m surprised that there isn’t a supplier of such for steel tubing. These brackets are often called lugs in bicycle building. Frankly they could allow for brazing too. However let’s not kid ourselves brazing will distort metal to some extent also.

    In any event I just wanted to point out that there are many potential options out there. If you are willing to experiment and understand the limitations it might be worth pursuing one of these ideas.



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Large router table capable of being dismantled and fit through a standard doorway

Large router table capable of being dismantled and fit through a standard doorway

Large router table capable of being dismantled and fit through a standard doorway