Newbie- Table top 80/20 build

[ynnek]

Well leth me introduce myself. My name in Kenny. I am a machinist at a custom liquid packaging plant. Ehere I work, we are thinking of purchasing a 4x8 industrial router for building setup parts for our rotary liquid packaging machines. These parts are made from either UHMW or Delrin.

To help sway the consensus about wether this will work for us, I had decided to build a small tabletop machine to make some of our really small parts & do some engraving. I decided to build this machine with no plans, you know, build it as you go. Everything seemed ok & the machine was mostly finished.

This is when I found posts on this forum about the lack of support of the 8020 linear bearings. What I figured out was too much play all of the linear slides. So I started shimming them. As it would go, they ended up too tight.

So after all of that I did not want to start over. I decided to put rods & delrin bushings in the current design. I will post some pics later on today.

I guess what I am trying to say is, don't you hate it when you are designing & building on the fly & there is an oops.

[LeeWay]

Never had an opps. All just mandatory design changes.

I look forward to seeing your pics.

I think the 80/20 slides would work well as drawer slides and glides or on machines that don't have much cutting force and don't require much accuracy. I think you would be better off using heavy duty drawer slides and everything gets better from that point on.

[solodex2151]

Kenny,

Normally in corporate environments, people want a turnkey solution with support options. Time is far more valuable to employers than the extra $5 grand they will save by having you building a machine. If they pay you to do it, at $10 an hour and assuming only 1/3 of the hours are productive (a very conservative figure believe it or not) and it takes 100 productive hours to design, build, and tweak the machine (again a conservative figure) they have already shelled out $3,000 in labor. Now, you can determine how much is has/is going to cost them in your labor based upon your rate, etc. Also, when you factor support costs and costs for machine downtime upon breakage the number grows even higher. If you are building the machine on your own time, more power to you. However, if they ask you to build the 4' X 8' machine I would present the same argument I gave here as the basis for buying a machine.

That said, I am not a big fan of bushings or the 80/20 linear slides. Since you already have the 80/20 going for you, I would seriously consider a bearing system. THK or Thompson products might be out of your budget, but there are cheaper alternative like Ahren's linear motion and power train products at cncrouterparts.com. They mount directly to the extrusion, are easy to design around, and are reasonably priced. VXB has some reasonably priced supported rails and blocks, but they don't mate nicely to the 80/20.

Nate

[ynnek]

Thanks for your input Nate. I guess I was not clear as to what I am doing with this tabletop machine. It is just to show what I can do with it & to explain to my GM what I can do with a larger machine. With that being said, if we do buy a large CNC router it will not be used in a production setting. I will use it to make setup parts for our rotary liquid filling machines on an as needed basis. These parts called "Change Parts" are generally made from 1/2" UHMW & sometime from Delrin. Being that the parts are to be made from plastic is why I have chosen to look at a CNC router vs a CNC Mill. To buy a mill that could make the parts for our largest machine would cost >$120,000. My manager asked me to build a small scale router machine & that is what I have done, in between current projects. I do not plan to build a large router here at work, but I will if that is what I am asked to do. You know how corporate politics can be. Once again Nate, thanks.