Gerber router

[martin54]

I realise this is mainly a site for vectric software & actual hardware help is not the main focus but having said that was wondering if any one on the forum owned an old gerber router & if so done anything to increase z travel.
I have an old system 48 & these machines were produced by Gerber for signmakers who would generally only work with reasonably thin materials. Because of this the bottom of the gantry is only 55mm above the machine bed.
At some point I would like to add a 4th axis to the machine which isn't an option at the moment with such a low z height (machine will not cut outside of table).
Best way I can think of at the moment would involve removing some of the existing machine table (possibly temporary measure while doing rotary work) & having a second table fitted to the bottom of the steel framing instead of the top with the 4th axis built on this lower table if that makes sense.

Will try & get something drawn up to better show what I was thinking about but if anyone has already got a way to increase z height travel I would be interested to know how they have done it.

[garylmast]

I think how I would do it, is cut a hole in the table top, saving the material to insert back into the top when the rotary is not in use, then build a frame work to support the rotary device underneath. You may even get creative and adjustment screws on the framework to raise and lower the framework.

You may also consider raising the gantry by adding spacers or adding additional material, that may even be easier.

Gary

[PaulRowntree]

Could you remount the spindle at 90 degrees (parallel to the table, parallel to X) then use the X axis to move towards/away from the centre of rotation?

As an example of Gary's idea, there is an image on the Joe's Hybrid site (image#29 of the gallery). I've always liked this design ...

http://www.joescnc.com/album/Joe%27s%20 ... index.html

Cheers!

[martin54]

Thanks for the feedback so far people always good to get others perspective on things.

Gary, The idea of cutting a hole in the table & building a frame to support the rotary was what I meant by this:

Best way I can think of at the moment would involve removing some of the existing machine table (possibly temporary measure while doing rotary work) & having a second table fitted to the bottom of the steel framing instead of the top with the 4th axis built on this lower table if that makes sense.

Maybe didn't explain it clearly enough but always good to know others are thinking the same way. The work table on these machines is an aluminium 'T' slot design with the aluminium slats being approx 100mm wide, these are bolted to a steel framework at either end & in the middle on a steel cross section. If I were to cut 6 or 7 of them in half so they could be removed/replaced relatively easily I don't think the machine would lose a lot of it's rigidity.

I've seen a machine on the tube where someone had raised the whole gantry by using a couple of aluminium blocks, it would be an easier thing to do as you say Gary but what put me off that idea is that it is fairly permanent. By fairly permanent I mean I think it would be to much mucking about & setting up everytime I wanted to do a rotary job so machine would have to stay like that most of the time. That could well affect the overall day to day running of the machine as it is going to make the whole gantry less rigid which will affect the materials I can cut & the speed & feed rates I can cut them at.

Paul, interesting Idea & certainly something that I haven't seen before. If I could come up with a way of rotating the spindle that was relatively easy to change over then that would probably work. Biggest problem for me with that idea is that when the spindle was rotated the axis would be switched about which would probably confuse the hell out of me lol. Think it would be relatively easy to set up in mach3 as a second machine though.

Will take a couple of photos when I am up at my unit tomorrow because that will help explain what I am talking about plus do a couple of sketches of how I thought I might be able to do it.
If I can get this bit figured out then the next questions will be all about 4th axis set up & where to get the parts from lol.

Thanks for the help so far gents,

[Dclifton2]

I had two ar400, you can put a spacer between the gantry and bearings. If you want to contact me off forum I can send you some pictures of what I did.
Don Clifton
Dclifton2@cfl.rr.com

[garylmast]

I bought my machine with a 300 mm gantry height, but it still didn't give me maximum clearance with my rotary device. So I tapped and threaded new mounting holes and raised the spindle, which gave me an additional 2-1/2 inches. When I'm not using the rotary, I just lower the spindle in it's cradle.

[martin54]

Having had some help from Don who has actually done what I am looking to do with the same type of machine it now looks like I will end up making a couple of blocks & raise the whole gantry. Be a while before I can get the money together for a 4th axis so no great hurry to do this but will post some pictures once it is done. May take me a while so don't look for an update to the thread to quickly lol

[PaulRowntree]

Does anyone remember seeing a novel idea by 'Bob' over at CNCZone about a year ago, where instead of a dedicated 4th axis he built a rolling pinion system along a rack mounted to the bed, parallel to the long gantry axis, so that translation along this axis caused the stock to rotate. I can't find the post now, can't remember Bob's real name, but he provided the rack and pinion patterns, and some photos of projects that I thought looked pretty good. It was about 3" of motion per full rotation.

I'd be interested to see if anyone else had successfully implemented his idea.

[Ronwoodson2]

At CNCsharktalk forum search for Bob's super simple 4th axis for tha thread

[PaulRowntree]

Thanks! here it is...
http://www.cncsharktalk.com/viewtopic.php?f=12&t=1521

Anyone tried it?

[zeeway]

Bob's design deserves an engineering prize. Ingenious.

Angie

[cac67]

Bob's design deserves an engineering prize. Ingenious.

Angie

I agree. Brilliant in it's simplicity, and no way you could do it cheaper.

[martin54]

I read the whole thread & was a little disappointed, Bob has done a brilliant job & could probably have made money from that idea rather than just share it with others yet despite him asking people to take the time to post what they had made using it only one guy bothered to add anything other than questions about how to use it.
There was some good input from one or 2 others so was good to see how it developed.

Might look into that a bit more as it now looks like raising the gantry is the way I will be going.