Re: 795, 895 (etc) DC motors
Cutting speed refers to cutting speed of materials. For example the cutting speed of cast iron as shown in Machinery’s hand book is 50 feet per minute.?
A complete list of cutting speeds of materials is listed in Machinery’s Hand Book.?
Most experienced machinists use this method to establish a starting point of RPM. As machinists gain experience these parameters become second nature and we estimate the speed in rpm.
Dick
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
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Re: 795, 895 (etc) DC motors
tomstechniques.com, which appears to be offline today published a chart with the formula that’s being discussed.? This is the chart and rule of thumb formula that I believe the original poster had intended
to express.
?
Scott
?
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From: [email protected] <[email protected]>
On Behalf Of Elliot Nesterman
Sent: Tuesday, September 3, 2024 2:07 PM
To: [email protected]; johnd@...
Subject: Re: [Unimat] 795, 895 (etc) DC motors
?
I imagine it's: CuttingSpeed = (RPM*4) / Diameter
But what measure to use for diameter, Imperial or metric?
1000RPM * 4 / 2" = 2000 inches/minute (166 ft/min)
1000RPM * 4 / 50mm = 80 mm/min (3.15 in/min)
1000RPM * 4 / 5cm = 800 cm/min (315 in/min 26.25 ft/min)
My guess is imperial inches, but who knows?
On 9/3/24 3:10 PM, John Dammeyer wrote:
CuttingSpeed = (CuttingSpeed * 4)/Diameter??? Missing a parameter here?
*From:*[email protected] [mailto:[email protected]] *On Behalf Of
*OldToolmaker via groups.io
*Sent:* September 3, 2024 4:55 AM
*To:* Keith S. Angus; [email protected]
*Subject:* Re: [Unimat] 795, 895 (etc) DC motors
Keith,
The formula for calculating cutting speed is four times cutting speed
divided by the diameter.
This has served me for over 50 years and never fails. I learned it in
trade school.
Dick
--
?OFF-SET-tailstock-center-65965#post105972
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<>?SMALL QC TOOL POST PLANS
<>?QUICK CHANGE LATHE TURRET
<>?MINI LATHE COMPOUND
PIVOT MODIFICATION
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Elliot Nesterman
elliot@...
"The finest jewel cannot disguise a flawed character."
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Re: 795, 895 (etc) DC motors
I imagine it's: CuttingSpeed = (RPM*4) / Diameter
But what measure to use for diameter, Imperial or metric?
1000RPM * 4 / 2" = 2000 inches/minute (166 ft/min)
1000RPM * 4 / 50mm = 80 mm/min (3.15 in/min)
1000RPM * 4 / 5cm = 800 cm/min (315 in/min 26.25 ft/min)
My guess is imperial inches, but who knows?
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On 9/3/24 3:10 PM, John Dammeyer wrote: CuttingSpeed = (CuttingSpeed * 4)/Diameter??? Missing a parameter here?
*From:*[email protected] [mailto:[email protected]] *On Behalf Of
*OldToolmaker via groups.io
*Sent:* September 3, 2024 4:55 AM
*To:* Keith S. Angus; [email protected]
*Subject:* Re: [Unimat] 795, 895 (etc) DC motors
Keith,
The formula for calculating cutting speed is four times cutting speed
divided by the diameter.
This has served me for over 50 years and never fails. I learned it in
trade school.
Dick
--
?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
--
Elliot Nesterman
elliot@...
www.ajoure.net
"The finest jewel cannot disguise a flawed character."
|
Re: 795, 895 (etc) DC motors
CuttingSpeed = (CuttingSpeed * 4)/Diameter??? Missing a parameter here? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of OldToolmaker via groups.io
Sent: September 3, 2024 4:55 AM
To: Keith S. Angus; [email protected]
Subject: Re: [Unimat] 795, 895 (etc) DC motors? The formula for calculating cutting speed is four times cutting speed divided by the diameter. This has served me for over 50 years and never fails. I learned it in trade school. http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
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?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
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Re: 795, 895 (etc) DC motors
3” probably won’t work with the standard threading tool. you’d need to raise the headstock to swing that.? Maybe the setup that uses a threaded rod or headless fastener in a chuck to the left of the pulley and a nut arrangement ?fastened to the base? There are several variations of that setup in the files/photos.
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On Sep 3, 2024, at 1:26?PM, Peter Brooks <peter@...> wrote: ? On Mon, Sep 2, 2024 at 10:11 PM, John Entwistle wrote:
What diameter Peter? I was able to cut a .750 x 32 tpi both external and internal on the SL with the threading attachment.
Thanks John - it could be pretty large (by Unimat standards :-)? up to 3", and 12 TPI is pretty chunky.
?
Having said that there will probably be much finer threads as well.
?
Cheers,
Peter
?
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Re: 795, 895 (etc) DC motors
?
this kind of cheap test controller is directly connected with ESC and can adjust on device the speed of motor.
Reverse spinning could be obtained by switching 2 phases between motor and ESC.
Aero RC BLDC motors tend to be open construction, higher torque and lower rev (for propeller efficiency).
Auto RC models are usually closed, slim and high rev. Their characteristic is given as xxx kV which means number of turns per V because the speed is proportional with voltage.
--
NapierDeltic
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Re: 795, 895 (etc) DC motors
On Tue, Sep 3, 2024 at 06:06 PM, NapierDeltic wrote:
...For spindles and even for lathe I would recommend also RC brushless motors...
Many thanks for the suggestion and link!
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Re: 795, 895 (etc) DC motors
On Tue, Sep 3, 2024 at 01:42 AM, Keith S. Angus wrote:
If you are cutting hard brass then you can make cutters from silver steel (drill rod)...
Thanks Keith, there's some great ideas there, and the free-standing motor could be one of the three DC scooter ones I have already.
?
I think the spindle would have to be inclined slightly to cut the thread at the correct angle?? These angles would change from item to item depending on the pitch.
?
How on earth would you make a cutter?? I guess you would start with the (for instance) 55 degree triangle profile at the end, then mill alongways to create individual teeth?? How many 'teeth'?? Apart from the U3 lathe I have the milling attachment (with fine feed), and the indexing / dividing attachment, so I guess there is no excuse!
?
?
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Re: 795, 895 (etc) DC motors
On Mon, Sep 2, 2024 at 10:11 PM, John Entwistle wrote:
What diameter Peter? I was able to cut a .750 x 32 tpi both external and internal on the SL with the threading attachment.
Thanks John - it could be pretty large (by Unimat standards :-)? up to 3", and 12 TPI is pretty chunky.
?
Having said that there will probably be much finer threads as well.
?
Cheers,
Peter
?
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I too have always used WD40 and recently I came across another make GT85 with PTFE and this works well too.
?
I would think kerosene would give off a nasty smell I don't know I have not tried it.
?
A few years ago I had to make and cut some very fine 2 1/2D in relief medals on the cnc I made a dam wall of putty around them and flooded it with Johnson's Baby Oil they turned out fantastic finish.
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Phill
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Re: 795, 895 (etc) DC motors
On Sun, Sep 1, 2024 at 08:43 AM, Paul Allen wrote:
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
?
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.
?
I also prefer a fairly well sealed motor for use when cutting metal. It seems the right thing to do.
?
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.
 ? ?
?
Here is my 2003 bench drill press with a 220W motor. Meanwhile the specs for motors were shifted from continuous to 3x power( W/kW) intermitent. Just paper work for advertising.
?
For spindles and even for lathe I would recommend also RC brushless motors.
?
?
They are relatively cheap and long lived, you can search for apropriate characteristics. There are plenty of tutorials on Youtube so I would not give a specific address...
Ok, here is an example and you could look at entire series related to Proxxon MF 70:
https://www.youtube.com/watch?v=sM5KqNiaeHQ
?
?
NapierDeltic
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I too use WD 40 for aluminium, works well, so well in fact I bought a gallon of it and a spray bottle.
------ Original Message ------
Date 03/09/2024 17:51:37
Subject Re: [Unimat] Cutting Aluminum
Kerosene works great for cutting aluminum, and it is cheaper than WD40, even when you buy it in bulk.
Years ago, maybe here or one of the other groups, someone recommended using WD-40 as a coolant/lube when cutting Aluminum.
I have done so ever since because I have found that I seem to have fewer problems than when using it rather than other stuff.
Just my $0.02 Your mileage might be different!
Dave
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Kerosene works great for cutting aluminum, and it is cheaper than WD40, even when you buy it in bulk.
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Years ago, maybe here or one of the other groups, someone recommended using WD-40 as a coolant/lube when cutting Aluminum.
I have done so ever since because I have found that I seem to have fewer problems than when using it rather than other stuff.
Just my $0.02 Your mileage might be different!
Dave
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Years ago, maybe here or one of the other groups, someone recommended using WD-40 as a coolant/lube when cutting Aluminum.
I have done so ever since because I have found that I seem to have fewer problems than when using it rather than other stuff.
Just my $0.02 Your mileage might be different!
Dave
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Re: 795, 895 (etc) DC motors
Keith,
The formula for calculating cutting speed is four times cutting speed divided by the diameter.
This has served me for over 50 years and never fails. I learned it in trade school.
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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Re: 795, 895 (etc) DC motors
If you are cutting hard brass then you can make cutters from silver steel (drill rod) and you don't need to harden them. If you do harden them and they get hot they will blunt, but you can let down the temper, re-shape them and harden them again. So you could make cutters to suit whatever thread form you need. I wouldn't call them single point, but more like the thread milling cutters already in use.
?
I wouldn't worry so much about the motor, but think more about the design of the spindle, then use a belt drive to connect it to a motor. Buy an ER11 collet holder on an 8 mm shaft and fit it into some ordinary ball bearings, in a bock of Ali, easily made by dowelling and bolting it to the cross slide and boring it through with drills and reamers in the main chuck. Height and alignment will be correct. Then you can make cutters with shafts up to 7 mm, or smaller as convenient. Then maybe fit the motor alongside or above the spindle. I don't think it would need much power - you can always take it slow.
?
The other problem is to hold the thin wall components without distorting them, but I imagine you have already worked that out. The same spindle can be used with ordinary milling cutters to make spigots and nests to support the rings.
?
Then you might find yourself building a whole new machine based around a rotary table, once you have developed your ideas further. A friend of mine did a lot of complex machining with a rotary table mounted on a mill - without CNC - but he spent time planning the jobs on CAD first.
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Re: 795, 895 (etc) DC motors
What diameter Peter? I was able to cut a .750 x 32 tpi both external and internal on the SL with the threading attachment.
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On Sep 2, 2024, at 1:23?PM, Peter Brooks <peter@...> wrote: ? Hello Nate, it’s connected really to my other thread for recommendations for stepper motors, controllers etc.
?
I would like to make some brass flanges and adapters for large format shutters and lenses.
?
A large part of endeavours with the tiny U3 is envisaging what would be successful… this is all entirely theoretical (and possibly also entirely mad) but I’m thinking of the headstock spindle and main lead screw being driven as slowly as you like with a stepper motor(s) in the correct ratio, and a single point thread cutter doing the work, spinning away on the auxiliary motor mounted on the slide.
?
I just can’t see a standard cutter scraping away being remotely successful, although maybe I am wrong. The largest thread would be a Whitworth at 12TPI.
?
At the moment it is - as they used to say about futuristic cars - just a ‘concept’.
?
I’ll have a look for those books - thanks.
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Re: 795, 895 (etc) DC motors
I totally agree.? Those are commercial speeds for something like a HAAS with massive flood coolant and a high speed spindle.? But it’s a starting point.? John ?
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From: Keith S. Angus [mailto:keithsangus@...]
Sent: September 2, 2024 4:54 AM
To: John Dammeyer; [email protected]
Subject: Re: [Unimat] 795, 895 (etc) DC motors? On Mon, Sep 2, 2024 at 06:42 AM, John Dammeyer wrote: Interesting to see the theoretical figures. I notice the power requirement is about 160 W, but the feed rate is almost 3 metres per minute, 50 mm per second. Since the lead screw is 1 mm pitch that means twiddling the handwheel at 3000 rpm, which is not going to happen. The handwheel is a constraint, especially as the table wiggles if you put too much force on the handwheel. There is a fix for this which I will try one day, Incidentally all my cutters are carbide - at this size that's all I can get. From my experience with carbide drills I expected them to break as soon as I looked at them, but the only one I broke I fed into a vice jaw by accident. None have failed during actual cutting. Theoretical speeds and feeds are fine for automated production, but for home jobs which are one-offs, and need some accuracy, nice and slow avoids costly mistakes. I was making some jigs for production. I took time and care to get them right. Once I was using them I just lopped off metal with what was once called gay abandon. If a few of them went wrong they just got binned. But the jig had to be right first. The big challenge with the little mill is to fit a DRO. Every set of scales I look at is either far too large for the space or costs far more then the mill. One answer would be to get a chunky scale and use it as the table, direct. Newall make one that might be small enough, but it's a bit expensive. Just looked at the Newall site - best to find the linear scales first and build the mill around them!
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Re: 795, 895 (etc) DC motors
Hi Carl, I only used the 4 flute because Keith stated he used that.? The calculator is Machinist Toolbox.
? It tends to go for the absolute maximum surface speed which then generates a huge spindle RPM.? On my CNC mill I’m limited to 3000 so I just cut back the surface speed until the RPM matches what I want to run the mill at. One of the nice parts is the depth of cut and axial cut. ? For example I’m about to profile and cut this piece on my mill.? 
? I don’t have the travel so I also have to flip it with alignment pins but since it’s CNC doing the cutting I’m never sure what depth per pass.? Hopefully this will work out and I’ll start with half the feed rate and mist cooling. ? 
? ? ? John ?
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From: Carl [mailto:carl.blum@...]
Sent: September 2, 2024 4:54 AM
To: [email protected]; johnd@...
Subject: Re: [Unimat] 795, 895 (etc) DC motors? Hi Keith and John: In your chart I noticed you call for a four flute cutter. In my experience four flute cutters tend to pick up aluminum chips and weld them to the cutter, often with spray coolant. Cool calculator! Carl. On 9/2/2024 1:42 AM, John Dammeyer wrote: 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 ? 
? ? 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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Re: 795, 895 (etc) DC motors
Hello Nate, it’s connected really to my other thread for recommendations for stepper motors, controllers etc.
?
I would like to make some brass flanges and adapters for large format shutters and lenses.
?
A large part of endeavours with the tiny U3 is envisaging what would be successful… this is all entirely theoretical (and possibly also entirely mad) but I’m thinking of the headstock spindle and main lead screw being driven as slowly as you like with a stepper motor(s) in the correct ratio, and a single point thread cutter doing the work, spinning away on the auxiliary motor mounted on the slide.
?
I just can’t see a standard cutter scraping away being remotely successful, although maybe I am wrong. The largest thread would be a Whitworth at 12TPI.
?
At the moment it is - as they used to say about futuristic cars - just a ‘concept’.
?
I’ll have a look for those books - thanks.
|
OldToolmaker
John Entwistle
NapierDeltic
Dave P.