I need to do some machining on very long parts (approximately 9' long) which is much longer than the X travel on my CNC machines.
I can run them on an open-sided bed mill so I can hang the parts off side of the machine. My X travel is around 40".
I'm looking to achieve locational tolerances of around +/- 0.05" over the length.
In the past when I needed to make long items like this, I have drilled holes every 3', slid the part over, indicated the hole as a new origin, and repeated as necessary to work my way across the length.
But this time I do not want to poke unnecessary holes all over the part.
Any ideas for different ways to accurately transverse a long part like this?
You could take a reference piece of material machined as a gage known length. Attach a self made clamp to the material and use the known gage as a solid measure from one stop/clamp to the other. It will be as accurate as your ability to clamp and move the stops without adding up error very much.
Not very good. You must concede the real situation and that is whatever you spend ime rigging up it still must be in tolerance. Besides actually machining it what is your function? It is ensuring your part is referenced properly and in tolerance.
You might do different things to accomplish referencing but they all involve referencing. Now if your customer does not want extra hole then you can figure out ways to do it yet it will involve a little bit of thought utilizing what you have to work with and a little bit of determined creativity.
You could weld ears of material on the side of the material. Set it up to machine equally spaced distances of say every thirty six inches and bump those onto a stop you have. Still you must reference the part though precisely.
Picture the I’s as stops of thirty six inches spacing machined one to another milled tac welded stops ground off or machined off at a point of after or during your process.
——————I——————-1————-1————-1————-1————-1————-1
Welding and removing sucks though a stop and a piece of material 36 inches long serves as a spacer between clamps of exactly 36 inches to move.
The Is are basically stops machined or ground off and finished to width at some point.
Actually with a 9 foot long part you would not have to use your 36 inch gage much and depending on how accurately you can attach a clamp as a stop and then move it against a fixed stop it may be well in tolerance. It is a attention to how well you can position your stops. You might even use a feeler gage to make sure any gap is noted.
One start reference point. Gage 36 inches long spaces exactly thirty six inches in between fixed clamp on left to next clamp right. Moving material from right of operator/or duh howdy guy to its left.
Clamp and un clamp home made clamps depending on timing, process and movement. You can use one secure pin stop to bump each position just calculate the movements.