HM45 Conversion (Yes another RF45 clone)

Hi everyone after lurking in here for about 5 years I have finally decided that I am going to convert my Hafco HM45 to CNC. (Aussie version previously sold by Hare and Forbes, machineryhouse.com.au)

I am looking for a simple 4 axis conversion using stepper motors and from what I have read here 250 oz should be good for the X and Y and I am hoping the A via a rotary table and will use 880 oz on the Z with some counter weight. Ordered first of the parts lastnight. I know some of you have used 450s on the Z but I want to test out the 880 to get ready for my next build which will be a Mechmate router capable of 2.4 x 1.2 sheet.

Initally I am going to use the stock screws and later on when bank balance recovers convert to ball screws however I think I have to convert my Z screw to start with and so am looking for some guidance here.

While I have found some really great threads in here, HOSS, over 200 pages in the new thread alone, Gd Marsh coming up on 70 pages, gid2 and others all containing great information most seem to have been doing this for so long you all have a good grasp on where and whose thread to look at for ideas and quite often when it comes to the details say things like " did this the same as others"

SOOO!oooo!!! I am looking for the easy way out here could people post the links to suitable threads on the Z Axis conversion of a "45" RF, PM, HM, ZX etc please. I find if I search on Z axis or Z-Axis I just get too many hits to even consider chasing down.

Perhaps we could even start an index thread of machine type and area of modification. What do you think, or is their an easier way that I just havent found yet.

Good luck with everybodys build as I change from "lurking" mode to "building" mode and a happy and safe festive season to you all.

Cheers Mal

Quote:

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Originally Posted by slipery

...........could people post the links to suitable threads on the Z Axis conversion of a "45" RF, PM, HM, ZX etc please. I find if I search on Z axis or Z-Axis I just get too many hits to even consider chasing down............

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Here's one interesting conversion thread http://www.cnczone.com/forums/bencht...sion_rf45.html


:cheers:

The Z axis is fairly straight forward.

I will be using a 2505 ball screw and nut from liniarmotionbearings on ebay.
They will do quality end machining on the ball screw if you provide them drawings.

I plan on drawing the motor mount and ball screw mount for my Z over the weekend and
will post pics in my thread. I also have a preliminary parts list.

Here are some that I have been following... To help locate stuff easier open one of the threads then look for "search this thread" near the top.
type in "Z axis" or whatever and it will search only that thread so you won't have to read the entire think.

I was thinking we all should do a RF45 WiKi page to consolidate some of this info.


http://www.cnczone.com/forums/bencht...sion_rf45.html

http://www.cnczone.com/forums/bencht...ered_rf45.html

http://www.cnczone.com/forums/bencht...ce_needed.html

http://www.cnczone.com/forums/bencht...g_started.html

and my thread here:
http://www.cnczone.com/forums/bencht...rehouse_-.html

Quote:

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Originally Posted by slipery

Hi everyone after lurking in here for about 5 years I have finally decided that I am going to convert my Hafco HM45 to CNC. (Aussie version previously sold by Hare and Forbes, machineryhouse.com.au)

I am looking for a simple 4 axis conversion using stepper motors and from what I have read here 250 oz should be good for the X and Y and I am hoping the A via a rotary table and will use 880 oz on the Z with some counter weight. Ordered first of the parts lastnight. I know some of you have used 450s on the Z but I want to test out the 880 to get ready for my next build which will be a Mechmate router capable of 2.4 x 1.2 sheet.

Initally I am going to use the stock screws and later on when bank balance recovers convert to ball screws however I think I have to convert my Z screw to start with and so am looking for some guidance here.

While I have found some really great threads in here, HOSS, over 200 pages in the new thread alone, Gd Marsh coming up on 70 pages, gid2 and others all containing great information most seem to have been doing this for so long you all have a good grasp on where and whose thread to look at for ideas and quite often when it comes to the details say things like " did this the same as others"

SOOO!oooo!!! I am looking for the easy way out here could people post the links to suitable threads on the Z Axis conversion of a "45" RF, PM, HM, ZX etc please. I find if I search on Z axis or Z-Axis I just get too many hits to even consider chasing down.

Perhaps we could even start an index thread of machine type and area of modification. What do you think, or is their an easier way that I just havent found yet.

Good luck with everybodys build as I change from "lurking" mode to "building" mode and a happy and safe festive season to you all.

Cheers Mal

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250 oz-in sounds awfully small to me for a machine that size. Those are better suited to something like an X2....

Regards,
Ray L.

Thanks for the replies all.
Ray what size would you recommend for the X and Y. It may well have been a smaller machine that I was reading about and got confused thinking it was a RF45.

slipery,

You could use 850 oz servos on your X/Y on a 2:1 pulley but I would suggest using the 1125 oz on your Z axis. Don't forget if you decide to use servos you also need the encoders for the servo motors.

Quote:

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Originally Posted by slipery

Thanks for the replies all.
Ray what size would you recommend for the X and Y. It may well have been a smaller machine that I was reading about and got confused thinking it was a RF45.

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Not having an RF45 myself, I wouldn't hazard a guess, but I'd be willing to bet the ones you have would make for a seriously under-powered machine. The only proper way to answer that question is to actually *measure* the required torque, and select the motors accordingly. I can't understand why people are so reluctant to take this simple step, but instead prefer to ask complete strangers for their guesses, or simply take a shot in the dark (and invariably end up with something inappropriate). It is a very simple thing to do, and is the only way to ensure you get a motor that is properly sized - not too small, and not too big. BOTH are equally bad!). I did this on both of my machines (a stepper-based X2 that does 270IPM, and a servo-based 9x49 knee mill that does 400IPM) and both perform extremely well, and never "lose steps".

Regards,
Ray L.

Quote:

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Originally Posted by eartaker

slipery,

You could use 850 oz servos on your X/Y on a 2:1 pulley but I would suggest using the 1125 oz on your Z axis. Don't forget if you decide to use servos you also need the encoders for the servo motors.

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I'm moving the 700# knee on my mill with an 850 oz-in servo. It should be more than capable of moving an RF45 head. 2:1 reduction on those motors will give you FAR more top-end speed than you can possibly use. Better to gear them down further, for added torque. Mine are geared 2.5:1 with 4-pitch screws, and will do 400IPM (which is TOO fast...).

Regards,
Ray L.

Quote:

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Originally Posted by HimyKabibble

Not having an RF45 myself, I wouldn't hazard a guess, but I'd be willing to bet the ones you have would make for a seriously under-powered machine. The only proper way to answer that question is to actually *measure* the required torque, and select the motors accordingly. I can't understand why people are so reluctant to take this simple step, but instead prefer to ask complete strangers for their guesses, or simply take a shot in the dark (and invariably end up with something inappropriate). It is a very simple thing to do, and is the only way to ensure you get a motor that is properly sized - not too small, and not too big. BOTH are equally bad!). I did this on both of my machines (a stepper-based X2 that does 270IPM, and a servo-based 9x49 knee mill that does 400IPM) and both perform extremely well, and never "lose steps".

Regards,
Ray L.

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Ray-

How do you go about measuring the required torque?


Sent from my iPhone using Tapatalk

Quote:

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Originally Posted by mrcodewiz

Ray-

How do you go about measuring the required torque?


Sent from my iPhone using Tapatalk

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Go to the hardware store, and buy a small "fish scale". Mount the screws you intend to use, set the gibs properly, attach an arm to the end of the screw, hook the fish scale to the arm, pull tangentially, and see how much force it takes to rotate the screw. Multiply the force by the radius of the point on the arm the scale is pulling from, and that's the torque. Add a generous safety factor, and select a motor with at least that much torque at the highest speed you intend to run. Takes a few seconds, and will let you pick a motor that is virtually guaranteed to work well. If people did this, we'd see far fewer threads about "missed steps", and there would be far less FUD out there about how "stepper motors ALWAYS lose steps".

Regards,
Ray L.

Thanks Ray for the latter words of clarification. If faced with a decision that I need to make and dont have all the facts I ask and hopefully someone repllies. If only one person replies then I need to check the facts a bit more but if confirmation is receieved from members who have done the same thing then that sounds like a resonable response. One reason people ask is that they dont know and I certainly was not sure on how to measure required torque and your latter clarification helped considerably but I am still a little in the dark as I can see that your system would work with sizing servo motors but as stepper motors quote holding torque it seems that method might only give you a starting point. I am guessing you would then need to check your figures on the motors torque/speed graph am I correct. Also isnt the depth of cut going to affect the required torque?