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795, 895 (etc) DC motors
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Bit off topic (sorry) but has anyone got experience with these smaller 24V DC motors?
This is not for re-motoring the U3 - which I’ve done already, a tremendous improvement - but for an auxiliary spindle.
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I believe the motor designation number relates to the physical size but I’m having trouble finding a general page as an overview of their characteristics. A google search brings up pages of items being marketed.
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Any advice and recommendations resulting from your practical experience would be much appreciated. I guess I’m looking for the best balance of size/weight and power, as it would be mounted on the slide. Quality and reasonable longevity are always good as well !
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I have a 24V supply with two PWM outputs, so that part is no problem.
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Thanks!
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This listing on ebay has a table with the dimensions and specs of the different motors
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Best Regards
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On Aug 31, 2024, at 2:37?AM, Peter Brooks <peter@...> wrote:
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Bit off topic (sorry) but has anyone got experience with these smaller 24V DC motors?
This is not for re-motoring the U3 - which I’ve done already, a tremendous improvement - but for an auxiliary spindle.
?
I believe the motor designation number relates to the physical size but I’m having trouble finding a general page as an overview of their characteristics. A google search brings up pages of items being marketed.
?
Any advice and recommendations resulting from your practical experience would be much appreciated. I guess I’m looking for the best balance of size/weight and power, as it would be mounted on the slide. Quality and reasonable longevity are always good as well !
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I have a 24V supply with two PWM outputs, so that part is no problem.
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Thanks!
Thanks John, that's useful.
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Peter,
All I can tell you is that I used two 24v Scooter motors I bought on EBay. They work flawlessly.
Dick
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A few years ago, for work, we were looking at 12V dc motors for a product we were developing.
I looked at 795 12v motors. They are cheap and noisy.
My advice, go for 24v scooter motors, better quality and quiet.
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Lez
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Everyone - I’ve already re-motored my U3 with DC scooter motors, and yes, they are great.
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I’m looking for a lighter DC motor to mount on the slide as an auxiliary spindle…
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I don't think those will have enough torque to be used as an auxiliary spindle. The 24v might, but they are typically used in low torque applications, often geared to multiply the output torque. You could certainly try it, but I think you will want at least a larger 24v 10k rpm or so motor. Look for spindle motors used for cnc mills.
Something like this will be a much better option: RATTMMOTOR 500W Spindle Motor CNC Air Cooled Spindle Motor ER11 12-100VDC 0.5NM 12000RPM + 52mm Spindle Motor Mount Clamp for CNC Router Milling Machine
Paul Allen
Everyone - I’ve already re-motored my U3 with DC scooter motors, and yes, they are great.
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I’m looking for a lighter DC motor to mount on the slide as an auxiliary spindle…
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I also used a XD-3420 12v DC motor, they are smaller and quiet and give good torque for the size. I know you can get them in 24v.
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Paul, Les, thanks for the advice and suggestions for alternatives.
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I’m in the UK, so the brands may be different but (as is common with goods from the far east) it looks like there is a generic product that is then ‘badged’.
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The XD-3420 is available on Ebay UK, item number 314725050514
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I can't see why you would need a 500 W motor for an auxiliary spindle on a machine that only needs a 150 W main motor. Certainly the power you need depends on just what you want to do, but it's best to keep a sense of proportion. For example my big old pillar drill has a ?" chuck and a 160 W motor, and quite happily pushes a half inch drill through steel - on low speed. But for most jobs the motor hardly slows.
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I also prefer a fairly well sealed motor for use when cutting metal. It seems the right thing to do.
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Still looking for something with high power in a small space to replace the motor on my Basic (PC). The standard motor is only 48 mm diameter, and the hole it has to fit in is only slightly bigger. One of those 795, 895 motors would fit and apparently give more power, but I don't like things like a starting current of 10 A - why? I've just touched the terminals of one across a small 12 V battery and there was no big spark when it made contact. I just don't believe it. But it did seem to run quietly - certainly compared to the nosy toothed belts on the Basic.
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A 160W motor on a drill press with a 1/2" chuck is highly unlikely. Typically they are 8 amp motors at 120v (4 amp at 240v). That would be a 960w motor. You are likely reading the spec plate wrong.
Another thing to remember is the 150w 24v motor is being geared down quite a bit in most cases and so it doesn't need the torque of a higher wattage motor. A direct drive spindle motor on the other hand does need the higher wattage in order to be able to maintain speed when using a multi-flute cutter. Plus, you don't have to use it at full power and can control the spindle speed without needing to resort to gear reduction.
And these motors are just an example of alternatives to a 775 motor. He could go with a 150w or 300w and probably be ok, depending on what exactly hse wants to do.
Paul Allen
On Sat, Aug 31, 2024, 10:28?PM Keith S. Angus via <keithsangus= [email protected]> wrote: The XD-3420 is available on Ebay UK, item number 314725050514
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I can't see why you would need a 500 W motor for an auxiliary spindle on a machine that only needs a 150 W main motor. Certainly the power you need depends on just what you want to do, but it's best to keep a sense of proportion. For example my big old pillar drill has a ?" chuck and a 160 W motor, and quite happily pushes a half inch drill through steel - on low speed. But for most jobs the motor hardly slows.
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I also prefer a fairly well sealed motor for use when cutting metal. It seems the right thing to do.
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Still looking for something with high power in a small space to replace the motor on my Basic (PC). The standard motor is only 48 mm diameter, and the hole it has to fit in is only slightly bigger. One of those 795, 895 motors would fit and apparently give more power, but I don't like things like a starting current of 10 A - why? I've just touched the terminals of one across a small 12 V battery and there was no big spark when it made contact. I just don't believe it. But it did seem to run quietly - certainly compared to the nosy toothed belts on the Basic.
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I retained the original Unimat pulley system in order to utilize the the full range of speeds and torque.
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
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The specs are often quite hard to comprehend (and believe!) on these imported items.
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Presumably the 500W quoted for that item could be when it is fed 100V, rather than 24V?
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The 775, 795 and 895 do look a bit on the flimsy side compared to the XD-3420 (which is more like the housing on the scooter type DC motors). And I have read reviews that say that the former that are described as brushless aren't actually brushless at all.
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Who can you trust these days! Ho hum.
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It is the diameter that is the limiting factor for mounting on the slide, and the weight I think to some degree.
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Isn't the XD-3420 only 30 watts?
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The specs are often quite hard to comprehend (and believe!) on these imported items.
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Presumably the 500W quoted for that item could be when it is fed 100V, rather than 24V?
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The 775, 795 and 895 do look a bit on the flimsy side compared to the XD-3420 (which is more like the housing on the scooter type DC motors). And I have read reviews that say that the former that are described as brushless aren't actually brushless at
all.
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Who can you trust these days! Ho hum.
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It is the diameter that is the limiting factor for mounting on the slide, and the weight I think to some degree.
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On Sun, Sep 1, 2024 at 06:43 AM, Paul Allen wrote:
A 160W motor on a drill press with a 1/2" chuck is highly unlikely.
I know what it is because I fitted it when I removed the original three phase motor. I know what the chuck is because the original was so battered I fitted a new one. It does everything I ask it to, including when I use blacksmiths drills on it allowing me to go up to 16 mm - although I use those slowly and carefully.
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The point with this additional axis is- what is it for? If the largest cutter going onto it is a 1 mm drill, it will not need much power. If the materials being cut are things like hard brass, or free cutting aluminium, it's easy. If it's on a Unimat tool post it will not be doing anything big, in cutting terms. I would use one in a setup that would really be the job on a rotary table (the chuck) with the cutter on the toolpost, rotating the chuck with a worm drive (I have the parts) and so doing large diameters without the usual problems of getting enough torque and avoiding chatter. But then the largest cutter I would use would be 3 mm diameter, because that's what I've got. I would expect a motor of about 50 W to do the job, if a little slowly. However the motors I have about that power would be a bit awkward to mount on a DB/SL. Easier on the U3 I use now, and even more so on the Basic if I ever get it running.
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One way to get the power onto the machine would be with a flexible drive. Got one of those handy too.
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Anyway, putting all that aside, the motor in my little Proxxon MF70 mill is quite compact and claims to be 100 W. Working speed is given as 5000 to 20000 rpm, and in the mill it works with small cutters, up to ?". The speed controller is also available. I don't know what voltage the motor runs on, but the mains voltage is AC 230 V. I have used mine mainly with 3 mm cutters on various aluminium alloys and hard brass. At normal cutting rates, and 5000 rpm, a four flute 3 mm cutter working on aluminium produces swarf that floats in the air. I haven't tried it at 20000 rpm.
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I got mine from Fluidline in Germany - dunno whether they will still sell to the UK.
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Motor: ?
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Controller: ?https://www.fluidonline.de/en/a-2513
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When I bought mine I found it was cheaper to buy from Germany even with the delivery costs.
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What’s a normal cutting rate at 5000 RPM with a 3mm 4 flute cutter?? What depth of cut per pass? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Keith S. Angus
Sent: September 1, 2024 2:10 PM
To: [email protected]
Subject: Re: [Unimat] 795, 895 (etc) DC motors? Anyway, putting all that aside, the motor in my little Proxxon MF70 mill is quite compact and claims to be 100 W. Working speed is given as 5000 to 20000 rpm, and in the mill it works with small cutters, up to ?". The speed controller is also available. I don't know what voltage the motor runs on, but the mains voltage is AC 230 V. I have used mine mainly with 3 mm cutters on various aluminium alloys and hard brass. At normal cutting rates, and 5000 rpm, a four flute 3 mm cutter working on aluminium produces swarf that floats in the air. I haven't tried it at 20000 rpm. I got mine from Fluidline in Germany - dunno whether they will still sell to the UK. Controller: ?https://www.fluidonline.de/en/a-2513 When I bought mine I found it was cheaper to buy from Germany even with the delivery costs.
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On Sun, Sep 1, 2024 at 10:14 PM, John Dammeyer wrote:
What’s a normal cutting rate at 5000 RPM with a 3mm 4 flute cutter?? What depth of cut per pass?
I was only doing about 100 mm per minute, I would guess, and taking out about 1 mm. I also had 3 and 2 flute cutters, in case the metal tended to clog the 4 flute, but I've never used them. The whole machine is not so rigid that you can take heavy cuts, but I was cutting grooves with a 90° pointed burr. That's fun at the point where the teeth are extremely fine and the cutting speed is low. I filled the groove with screen wash and it stopped it getting clogged. I was mainly machining anonymous chunks of aluminium. Apart from that I was setting it up as a precision saw using the cut-off discs from their little bench saw, chopping up small stainless tube, and other jobs like that. Some worked well on my SL, others on the mill. I even managed a few reasonably high precision operations on my big (compared to my other tool) pillar drill.
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I have never bothered much with cutting speed and depth analysis.? I put in an end mill, take a very light cut, and progess from there.??
I am unsure about trying to mill with a pointed burr.? To cut a groove like that, it may better to use a regular end mill with the head tilted at 45 degrees if your macine allows this.
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Hi Keith, You’re good on the depth of cut at the max based on Machinist tool box.? ??I reduced the Surface speed down to 155 SFM to get the 5000 RPM you were using.? The max depth of cut is 0.04724” which is 1.2mm. ? I chose 6061-T6 as the generic aluminum scrap pieces.? Clearly you could go much faster than what you are doing but then the machine itself factors into that. John ? 
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From: [email protected] [mailto:[email protected]] On Behalf Of Keith S. Angus
Sent: September 1, 2024 5:59 PM
To: [email protected]
Subject: Re: [Unimat] 795, 895 (etc) DC motors? On Sun, Sep 1, 2024 at 10:14 PM, John Dammeyer wrote: What’s a normal cutting rate at 5000 RPM with a 3mm 4 flute cutter?? What depth of cut per pass?
I was only doing about 100 mm per minute, I would guess, and taking out about 1 mm. I also had 3 and 2 flute cutters, in case the metal tended to clog the 4 flute, but I've never used them. The whole machine is not so rigid that you can take heavy cuts, but I was cutting grooves with a 90° pointed burr. That's fun at the point where the teeth are extremely fine and the cutting speed is low. I filled the groove with screen wash and it stopped it getting clogged. I was mainly machining anonymous chunks of aluminium. Apart from that I was setting it up as a precision saw using the cut-off discs from their little bench saw, chopping up small stainless tube, and other jobs like that. Some worked well on my SL, others on the mill. I even managed a few reasonably high precision operations on my big (compared to my other tool) pillar drill.
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John Entwistle
OldToolmaker
Les Orton