How much Z Axis do you need

[DaFlea]

I am refitting a old Quick Circuit Model 7000 circuit board prototyping machine manufactured by T-Tech, Inc.

The machine by itself is very solid, it is constructed completely in Aluminum about 1/4" thick and weights about 90lbs. The problem is the spindle assemble is lowered by a solenoid, thus there is really no z axis to speak of. So I am going to having new parts machined so that there is more room between the table and the bottom of the gantry.

My question is how much clearance do I really need? From what i can see by everyone’s design there can be limitations to what you can cut or how deep you can into a material. Is there some kind of rule of thumb to go by.

The actual cutting area is 13" x 19" so I’m thinking like 5" to 6" inches of clearance but I am unsure what the ideal height should be.
Any help on this would be great
Doug

[thegimpster]

I have a quick circuit at work (Expensive @$$ machine), If it works and you have the IsoPro software i would try to sell it. I saw one used for $10k. Not saying that you could get this much, but... Plus could I have a copy of the software, our install cd is thrashed. I tried contacting the company and it did no good, not even a reply to say 'ha ha your stupid'.

Back to your question. If you want 5 inches of clearance I would build your gantry sides about 10 inches or so. This gives you five inches up from the base and five inches to mount your stuff in. Of course you sould go lower i guess, like 8 and have 3 inches to mount your Y and Z axis on. But if you have the controller, power supply, and software, and everything works, sell the darn thing if you can and buy/ make one, and give me a copy of the software ;

[jdell42]

My question is how much clearance do I really need? From what i can see by everyone’s design there can be limitations to what you can cut or how deep you can into a material. Is there some kind of rule of thumb to go by.

This depends on what you plan on doing with it. If you still plan on making PCB's then you are ok with the Z Travel. If you want to use if for other things then most people have 5-6 inches although for flat stock 3-4 would be fine.

[LeeWay]

It is all really a design and intentions question. I have 4" Z clearance on my router. It was designed mostly for flat work and sheet goods. Now if I remove the tables for an odd ball thing, I could theoretically have 5.5" clearance.
I have 9" clearance with my mill. It was designed to cut flat work and to ut odd shaped stuff as well as things mounted in vises and fixtures.

One rule that you can go by is the higher the Z clearance, the stronger the Z and gantry will need to be built. It's easy to design a tall or high clearance Z axis, but the trick is designing out twisting and flexing. Kinda where the rubber meets the road, this is the first area that actually sees the cutting stresses. If this part is poorly designed, the rest of the machine can't overcome that inaccuracy.

[DaFlea]

I have a quick circuit at work (Expensive @$$ machine), If it works and you have the IsoPro software i would try to sell it. I saw one used for $10k. Not saying that you could get this much, but... Plus could I have a copy of the software, our install cd is thrashed. I tried contacting the company and it did no good, not even a reply to say 'ha ha your stupid'.

Back to your question. If you want 5 inches of clearance I would build your gantry sides about 10 inches or so. This gives you five inches up from the base and five inches to mount your stuff in. Of course you sould go lower i guess, like 8 and have 3 inches to mount your Y and Z axis on. But if you have the controller, power supply, and software, and everything works, sell the darn thing if you can and buy/ make one, and give me a copy of the software ;

Yes I know they are expensive and this one is basicly brand new it has been sitting around for years. I got it because no one knows where the controler box is. The software is somewhere but I dont know anything about it comming on CD's. this was purchased back when there software was on 3.5 disks. Ill look around for it but dont get your hopes up.. I have the user manual in front of me if you want that lol

5 inches is about what I figured would be the norm but wanted to see what others have done. If anyone is interested in buying the Spindle assembly let me know cause I am thinking of Ebaying it. The specs state 8,000 to 23,000 RPM

Doug

[andy_ck87028]

One rule that you can go by is the higher the Z clearance, the stronger the Z and gantry will need to be built. It's easy to design a tall or high clearance Z axis, but the trick is designing out twisting and flexing.

I wholly agree with the sentiment expressed, however I'd like to suggest a variation on it.

Maximum rigidity will occur when the z axis has minimum extension. Consequently, hobby machines being hobby machines unless you chuck in a lot of money, the likelihood of movement on full extension is quite high.

So, design your machine with a variable height table. When you are doing sheet work, have the table up high and reduce strain on your z axis; when you are doing deep work (often for smaller size material), drop your table. Alternatively, have a removable section on your table for deeper work.

Perhaps put also put your fourth axis within the removable section of the table.

Just thinking outside the box

Andy

[DaFlea]

I wholly agree with the sentiment expressed, however I'd like to suggest a variation on it.

Maximum rigidity will occur when the z axis has minimum extension. Consequently, hobby machines being hobby machines unless you chuck in a lot of money, the likelihood of movement on full extension is quite high.

So, design your machine with a variable height table. When you are doing sheet work, have the table up high and reduce strain on your z axis; when you are doing deep work (often for smaller size material), drop your table. Alternatively, have a removable section on your table for deeper work.

Perhaps put also put your fourth axis within the removable section of the table.

Just thinking outside the box

Andy

Andy,

This box is allready built so there will not be any mods to the table. However I understand what your saying. I havent ever put any though in the design of a table moving in the Z Axis, but I think it would end up being a more diffcult build.

[andy_ck87028]

I havent ever put any though in the design of a table moving in the Z Axis, but I think it would end up being a more diffcult build.

variable height table fixed at three heights through four vertical pillars each with 3 holes at 0, 2", 4".

Can be added on later....

[roygbiv]

i am in the process of modifing the same m/c
so far i have added 4" blocks on both sides of the gantry and added a z-axis with a trend spindal it is very much being made up as i go along.
how are you getting on with yours?

martin

[alexis221]

I am in the process of building my cnc router and I have 10" thk's and my gantry to the table surface is 5.5 inches. I think I have a solution in getting 5 inches of movement with these slides in how I mount the router and also the top plate to the slides. Also removing the table surface I gain another 3/4 of an inch. Also can I can add more to lift the work piece closer to the router. I really should go with 12 inch slide but don't want to pay the price for 2 xtra inches.