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  1. #1
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    Jul 2008
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    PM-25MV vs G0704

    So I have been doing a lot of reading and watching videos, and would like to hear from those more experienced at this than I.

    Which machine would be better to do a conversion. This would be based on things such as:
    1. Build instructions / threads available
    2. Availability of plans to make conversions
    3. Availability of quality conversion kits
    4. Additional enhancements once the base machine is converted to CNC
    5. Availability to add 4th and 5th axis.

    I realize there are those that would say "I did this one and I prefer it", but I am looking for a comparison in order to make an informed decision.

    Maybe someone has done this type of thing already. If so, please point me to it. With all the talent on this site, I believe there is a good comparison to be had.

    Thanks in advance,
    Dan

  2. #2

    Re: PM-25MV vs G0704

    4th and 5th axis isn't really a concern for the base machine. There aren't any commercially available systems for these size machines I am aware of, so you will probably be looking to build your own 4/5 axis for either option. If you are serious about 4th and 5th axis, you will want to pick your controller hardware/software carefully.

    The G0704 is certainly a well documented and well supported conversion, not that the PM machine isn't, but the G0704 has years of knowledge (threads) behind it.

  3. #3
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  4. #4

    Re: PM-25MV vs G0704

    I'd never seen that video, definitely interesting. I live about 15 minutes from Precision Matthews, but bought a used Grizzly 3 years ago because I found one with loads of tooling and fixturing for $1500.

    This in mind, some things definitely look better with the PM, the column being the primary contender. However, I don't think for this size machine it matters much. Considering that building a machine requires tuning of steppers, adjusting ways, rebuilding ballscrews, adjusting thrust bearings, setting spindle bearings, buying spindle motors, new belt drives, tooling, work holding, measuring equipment, software, controller hardware, limit switches, enclosures, flood coolant, lighting, way covers, steppers covers, shielding wires, probes, tool length offset measurement, and a never ending list of other **** I don't think it really matters. My CNC G0704 consists of like 6 original parts at this point. I assume the PM machine will be the same by the time you convert it. The biggest factor in performance will be all of those things you do yourself, not the barebones machine.

    Though if you can get all of those DIY factors really going, both the G0704 and the PM will be over powered and under built. If you really want something to grow on, start looking bigger.

  5. #5
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    Re: PM-25MV vs G0704

    I've used a number of G0704s and one PM25. They're night and day. The PM25 has its little shortcomings, but it's like buying a new German made AUDI versus a beat up old Mexican made VW. You can tune up a G0704, but the PM25 comes already working better than most tuned up G0704 machines. I find it to be a little more rigid when it comes to taking larger cuts, and the belt drive is a dream. For the CnC conversion, I understand it's a lot less work for the PM25 since there is enough room under the saddle and you don't need to mill a pocket for the ball nut. Unfortunately the PM25 kits are more expensive and harder to buy. I think if you are stretched to every last dollar, get the grizzly, but if you want a better overall machine, get the PM unit. That's what I did.

  6. #6
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    Re: PM-25MV vs G0704

    @CS900

    Excellent comparison video. I'm guessing at nearly 400 lbs these mills are somewhat unwieldly for a "loner" (no buddies or neighbors to call upon) to install and move around even with column separated from base. Any links to lifting, installing and moving strategies?

  7. #7

    Re: PM-25MV vs G0704

    My father and I carried my G0704. I removed the table and the steppers beforehand. My father is 69 and I'm 32, though my dad is probably the more fit of the two. If you don't mind taking it down to individual parts or purchasing an engine hoist you will easy be able to do it on your own. When I brought my G0704 home I moved on an engine hoist all by myself. That included out of the truck and into my basement workshop.

  8. #8
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    Re: PM-25MV vs G0704

    The G0704 allows for the Y-axis travel extension whereas the PM's column to base design does not allow this. The stock y-axis travel is limiting especially as your skills advance.

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  9. #9
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    Re: PM-25MV vs G0704

    I took a piece of parachute line and ran it around the column and up to a hole in the rafter above the mill, then used the column's Z travel to lift the mill. A bit of hackery, but just wanted to prove it could be done. 2 adults lifted the unit up to the bench with ease. If you remove the column, it is reasonable for 1 person to lift. If you get the Grizzly unit, you probably have to take the column off anyway since many of them aren't even mounted straight. Of the 4 g0704's I've helped with, not a single one was trammed to under 0.005", while my PM25 showed up at under 0.0001". In the ones I looked at, it only took scraping off the gobs of cast chips to true them up enough to be serviceable. The quality difference between the two mills is significant. The grizzly column is mounted differently too and this may also explain its comparative lack of rigidity.

  10. #10
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    Re: PM-25MV vs G0704

    The mills are not 400 pounds.

    I weighed each part on both mills and each part except the table coming in at about 70 pounds and the same for both mills. The head with motor 70, base 70, column 70

    I move them around in parts by myself and its easy. The table being the only fairly heavy part.

    As for which is better each has its good points. There is a 704 with a belt drive and brushless motor so that should be better but I think it was single speed.
    youtube videos of the G0704 under the name arizonavideo99

  11. #11
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    Re: PM-25MV vs G0704

    Good stuff....Thanks guys.

    I weighed each part on both mills and each part except the table coming in at about 70 pounds and the same for both mills. The head with motor 70, base 70, column 70
    Well, this just about erased all my lifting/moving concerns...Thanks!

    I notice the PM-25MV appears to be on backorder, is this the norm? Also, does anyone expect the brewing TTT (Tariff Tit for Tat) with China to have an effect on the pricing of goods like these in the near future?

  12. #12
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    Re: PM-25MV vs G0704

    Talk to PM about when they expect their next shipment. It is worth waiting for. Nobody knows what the tarriffs will mean. Any news like this results in a jump for consumer prices, even if the costs haven't changed... yet.

  13. #13

    Re: PM-25MV vs G0704

    I buy a number of products direct from China. Prices went up 20% the day the tariffs were announced despite not being included. Trade wars are great.

  14. #14
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    Re: PM-25MV vs G0704

    Does anyone know of a power drawbar system / kit that is available for the PM-25MV? I did a search and did not get anything but a manual system.

  15. #15
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    Re: PM-25MV vs G0704

    A bit off topic, but I have been thinking about how to do one, coupled with a servo drive for tapping. It might also be worthwhile to look at something like that TTS system, but I'm not there yet. I've been promising a build thread on mine but finding the time to make the parts is a problem.

  16. #16
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    Re: PM-25MV vs G0704

    Hackish,
    Thanks for the response. Since I am new to all this and doing my best to learn and ask from the pros, I am thinking of eventually doing an ATC. I have a habit of going the route when it comes to building something. Excuse my ignorance, but what is a "TTS" system?

    Kind Regards,
    Dan

  17. #17

    Re: PM-25MV vs G0704

    TTS is the Tormach quick change tooling, it's also used by Novakon and maybe others. It's a good system that basically adapts the R8 spindle for quick change.

    For tapping I use a servo drive but with a rotary encoder. My servo only pulses 6 time per revolution, so a rotary encoder is much better, especially for very fine threads.

  18. #18
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    Re: PM-25MV vs G0704

    Quote Originally Posted by CL_MotoTech View Post
    TTS is the Tormach quick change tooling, it's also used by Novakon and maybe others. It's a good system that basically adapts the R8 spindle for quick change.

    For tapping I use a servo drive but with a rotary encoder. My servo only pulses 6 time per revolution, so a rotary encoder is much better, especially for very fine threads.
    CL_MotoTech,

    Thank you for the response. I looked at this unit and it is very nice. Would be fun working on one like it. I was looking at the Hoss version of ATC on Youtube. Here is the link to one of the videos. Hope it is OK to post the link. If not, I apologize.
    https://www.youtube.com/watch?v=iDT693Zv_wE

    Dan

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