Are 2 heads better than 1??

[ernie_balch]

I plan to buy a new 96x60 alpha and am thinking about getting 2 router heads. Most of the signs I carve take 2 tools and I would like to set up the job and have the whole thing cut while I am doing other things.

Questions: Does it work without problems? How do you get the different router heads aligned to the same program zero?

thanks
ernie

[davidp]

Ernie,

I use two Z's, one router and one spindle. The spindle does most of the work and the 2nd router does the smaller stuff. The only problem you have is to ensure that you set up your offsets very, very accurately. Even then you will sometimes get cuts that dont perfectly line up, However if you work with the inaccuracies and devise strategies to reduce the errors, you will find that it will save time in a day.

Other times it is quicker and easier to just change bits on the Spindle. If I had to choose between a spindle or two Z's with routers, the spindle would win every single time.

Now an air drill is a different matter but that would depend upon your usage. I would love to swap the router for an air drill, I just need to find the right drill and it will be done.

My two bobs worth.

[ernie_balch]

I thought the two routers would align perfectly once the distance was established. Is there any reason to think a new Alpha would perform better?

ernie

[davidp]

Ernie,

Assuming that your two z carriages are perfectly vertical in both x and y and do move perfectly perpendicular to both x and y, and then assuming that the spindles of both routers are perfectly parrallel to the z carriage, Your Y car must also be in perfect alignment as must your x rails, then nearly always will the cutters be in alignment. Note I say nearly always, because you then have to allow for collet runout, cutter differences etc. You will also have to take account of slight differences in the steps and the slight error inherent in the controllers.

In most cases with careful calibration of your Bot you can almost eliminate any discrepancy but remember that the eye will instantly notice a 0.1 mm difference. An error of say 1 mm in a row of shelf holes may not be significant or even detectable, but a 0.05mm difference between a chamfer and a profile on a 200 mm diameter circle will stand out like the proverbial.

My experience is with a PRTAlpha, I dont believe that a second z is available on the PRS.

As I said in my previous post Two Z will save time but you must be aware of the limitations and I must re iterate if you have to choose between two Z's with routers or one z witha spindle the spindle would be my first, second, and third choice. The time you spend changing bits on a spindle will be more than saved by better and faster cuts which means greater output and less hand clean up of parts.

My two bobs worth.

Regards,

David

[ernie_balch]

Thanks David, you have convinced me to buy a spindle. I have a quote for a dual head PRS, but they didn't mention the alignments required, I can see that would be very difficult. People seem to be having trouble just keeping the X&Y axis at 90 degrees, I can see that a dual head is just asking for more problems.

ernie