Opinions needed on purchase vs buiding some components

[johnm]

Folks -

Okay, we're crunching numbers for the purchase of a 'bot and I'm cutting and pasting dollars in Excel. I'm working on various options and need your feedback.

Some of the parts and accessories can be home-built, from what I gather. Is it reasonable that one could build or fabricate the Z-Zeroing Plate, Proximity Switches, and the Emergency Stop Button? That adds up to $325, and it doesn't look like there's much "there, there" by way of Hardware - Are there software or drivers that goes with these components? I am not "agin" spending the money, but that's *almost* airfare from the West coast to Raleigh for training, for what looks like about 20 bucks in hardware...

Okay, next question - 48" or 96". The wife and I have a 24x32 shop and have the space, sort of... The larger unit is a little big for what we expect to be using it for (mostly a HUGE 2D job cutting out trim) but want to take a larger view of things as well.... Do any of you with the 48 wish you'd gotten larger? Or are any of you with the 96" tired of walking all the way around it... You know what I mean.

Now, Additional Z travel... Can you give me some practical applications where the additional travel would be useful? I can see that if you were milling into the ends of something - table legs for example, that the additional headroom would be nice. What else? My head spins reading through all of these posts in the various categories, and the possibilities are wide ranging. We only want to buy once, and buy right, so I'd like to hear from those with more experience.

Thanks in advance for your comments.

John
Lakeport, CA

[gerald_d]

John, you sound like a practical bloke - you can supply all those accessories yourself with very low risk. They do not have special "drivers". You could also build your own table. (I think that one E-Stop is already supplied as standard)

After a couple of years and many hours reading this Forum, I can't remember a single person regretting that they went big rather than small. (If you really want to get adventurous, buy the 96" and saw the rails in half - when you want to go bigger, join them up again
)

For milling the ends of things like table legs, most of us do that over the edge of the table, or through a hole in the table. Additional z-travel adds a large degree of structural flexibility to the machine, which can cause things like vibration.

[mikejohn]

John
read the long 3 part thread on building your own table.
Theres a lot of good thinking about the machine in general in there.
Think about hold down.
Some here
think simplicity is best, others advocate vacuum hold down.
I really dallied about before getting my blue monster, now it's taking me into realms I never knew existed.
I never expected to be putting full sheets on the table, but now I am lots of the time.
Im also making money in an area I never ever expected. I think Ive found a niche market

...........Mike

[jsfrost]

If you have time and little money, built the simple acessories yourself. Or the opposite.

I originally planned on making my own prox switches, and have easily spent a day exploring options and costs, but I never got to it. For the work I'm presently doing, they don't seem that necessary. Others will feel differently.

[simon]

John
All the above are easily fabricated.
As regards the half-bot, you will come to regret having to cut 8 by 4 sheets in half just to load them. Go for the big one.

[richards]

I left my proximity switches in the box for almost a year before finally understanding that they can also be used to zero the machine. Now I use them every morning as part of the calibration routine (and sometimes several times a day to 'fix' things when the power goes out.

Z-zero switch is just a piece of aluminum, a length of wire, and an alligator clip. A year ago, as a new shopbotter, it was well worth the price.

If you can find the room, go with the larger machine. I have the 120-60 model in a 20 x 22 shop (garage). The five foot width is necessary to cut full sheets of baltic birch plywood and the extra two feet of X-axis is used to park the carriage out of the way for easy cutter changes. I left that section of the table uncovered (no spoil board).

[gerald_d]

We have run without prox switches for many years, but our SB is pre-Alpha and it supposedly only creeps along compared the new machines. If you don't get prox switches, you are probably going to need that big table so that you don't run off the rails by accident.

[brian_harnett]

I am glad I bought the prt96 just last week I made 2 12' signs for a real estate building even with the 96 the signs had to be indexed and cut moving it on the table.
You can save a lot making your own table I think mine cost about 250 and I used aluminum I beams for the main rails.
The stop and proximity switches I bought with the machine I did make my z zero plate though.

[erik_f]

For the sake of ease I went with the SB supplied switches and other goodies...knowing I could make them my self...but also just wanting things to work out the first time and not deal with the headaches. As far as size goes...I'm trying to find a better place to put my cabinet table saw...even though it is one 1/4 the size of the shopbot...it seems to take up more space in my shop because of the fact its in my way more than anything these days.

Erik