ALSGS Power Feed – How Fast Is Each Increment?

[Chris Edwards 1Participant @chrisedwards1]

Hi,

I have an ALSGS (AL-310S) which I believe has a speed range of 0-200RPM.

The unit is marked with increments of 0-9 (which is it’s top speed).

Am I right in assuming that each increment roughly stands for 22RPM and that if I was to consult a ‘Feed Rate (mm/rev)’ table for my milling tools I would be able to use the ‘f’ number as the RPM (depending on material and depth / angle of cut)?

Many thanks for your help and time?

Chris.

[Michael GilliganParticipant @michaelgilligan61133]

In my opinion, Chris … that seems highly unlikely

Please see page 13 of this:

https://www.aikrondro.com/wp-content/uploads/2022/03/ALSGS-Power-Feed-User-Manual.pdf

MichaelG.

[Chris Edwards 1Participant @chrisedwards1]

Hi Michael,

Thanks for getting back to me so quickly.

Page 13 seems to be the end of the trouble shooting section and the circuit diagram (which is beyond me to read).

Do you know what the increments of the 0-9 dial are or can you explain this page to me?

Many thanks,

Chris.

[JasonBModerator @jasonb]

As these feeds get fitted to machines with both metric and imperial leadscrews there is no specific revs per mark.

Best thing to do is get out your stopwatch and time the travel over a given distance which will allow you to work out the feed rate at each position. That is what I did with my SIEG ones.

If your tools give a fz figure then you can work out a feed rate using that and the cutting speed for the material and tool diameter to work out a ball part feed rate.

[Michael GilliganParticipant @michaelgilligan61133]

The circuit diagram shows a brushed motor, with a simple control circuit

… inherently likely to have a non-linear relationship between the numbers and the motor speed.

MichaelG.

.

I’m sure the experts will be along soon to explain the minutiae

[Chris Edwards 1Participant @chrisedwards1]

Thanks Jason,

That’s great advice, I’ll give that a go!

Cheers, Chris.

[JasonB]

On JasonB Said:

As these feeds get fitted to machines with both metric and imperial leadscrews there is no specific revs per mark.

That does not seem correct as a statement. The ‘language’ of the screw is irrelevant to the motor and its controller.

Indeed, you would expect ‘5’ on the motor to give the SAME rpm whatever it is fitted to.

Hence, I would say there most surely is a specific rpm for each mark. The rpm increment between marks is likely to be non-linear, as pointed out above.

The feed rate produced by setting the dial to any particular mark will of course be dependent on the pitch of the screw to which it is attached.

—

A modern option is a tachometer app for your phone. See what the app needs as a reference and let it tell you the motor rpm for each dial division. Factor in your leadscrew pitch to calculate a feed rate.

[mgnbukParticipant @mgnbuk]

Hence, I would say there most surely is a specific rpm for each mark. The rpm increment between marks is likely to be non-linear, as pointed out above.

Unless the controller has some form of speed feedback, it is unlikely that the speed will be consistent with variations in load, so any markings related to speed would probably only apply to a no-load condition ?

The Chester 3 speed mechanical feed gearbox I fitted to my FB2 clone (the Chester box appears  to be a clone of the Emco 3 speed box) has feed rates shown, but checking with a stopwatch against a simple capacitive scale showed the printed values to be incorrect – they appear to have been calculated for a 60Hz motor, not 50Hz so are optimistic.

 

Nigel B.

[MacolmParticipant @macolm]

This power feed is the same generic design as the Align units (if not identical), and the circuit diagram is also near enough identical. It is a “traditional” universal motor SCR controller circuit that has been around since the 1960s, and none the worse for that if you need an effective but low cost speed controller. It is perhaps more cunning than first impressions, and incorporates stabilisation using the motor back EMF, depending for that on the magnetic remnance in the field laminations.

It is however certainly not a precise speed controller, and the characteristic of the control knob will be nearer to a logarithmic law than linear. On my Mill/Drill, the useable table speed range is approximately 0.25mm/second up to 7.5mm/second, and I find this almost always allows setting a satisfactory speed. If you must know the feed per cut, then some skool rithmetic is necessary, presuming you know the spindle speeds.

[PeteParticipant @pete41194]

Those look like the usual clone of the Servo power feeds. And if you’ve never used one yet, then in my opinion there definitely one of the better – almost best items you can add to a mill. As someone else has already pointed out, those dial markings for feed rate will be non linear and inexact. At least they are with mine. Tool diameter, depth of cut, extra large and heavy work pieces, even the type of material being cut or a really dull tool are all going to put a different and variable load on the power feed even if those dial marks were in fairly accurate steps. It’s still not that difficult to set something close to the correct feed rate though. Other than maybe brass or cast iron, if your producing really tiny and thin chips or powder, your feed rate is much too low. Too fast and the mill and power feed will let you know. Use it for a while and that experience will start to allow some pretty accurate guesses and estimates of what you should be using versus what your doing. For fairly small diameter end mills it’s a lot tougher since there so easy to break. But they really shouldn’t put much load on the power feed, timing the unloaded feed rate the table will move and calculating the chip load per tooth still helps a lot in my opinion.

[Chris Edwards 1Participant @chrisedwards1]

Hi Everyone,

Thanks for getting back to me so quickly, you know your stuff!

What I ended up doing is the following:

1. I set my mill up with the vice / material I was planning on machining and timed how quickly it travelled between two points at the different settings (1-9).

2. I then calculated the ‘cm/s’ value using the following website; https://www.omnicalculator.com/everyday-life/speed

3. I then converted my ‘cm/s’ value into ‘mm/min’ using the following website; https://www.unitconverters.net/speed-converter.html

4. I was then able to use this data to compare to the ‘f – mm/min’ readings that came with my mill tools.

I’m not sure if this was the best way to do it but it produced good clean cuts.

Hopefully this will help someone else who was wondering about the same issue.

Cheers,

Chris.

[not done it yetParticipant @notdoneityet]

Does it really matter?  I simply set my feeds to somewhere near a sensible rate and adjust for optimum load/cutting/finish.

[Chris Edwards 1Participant @chrisedwards1]

Hi,

It probably doesn’t matter to an experienced person, but for someone starting out it’s good to have a rough idea of where all the settings should be.

Cheers, Chris.

[PeteParticipant @pete41194]

It better matter, there’s more than a few material types that seriously work harden almost instantly if you let the tool rub due to any feed mistake. Multi tooth cutting tools such as slitting or slotting saws, face mills, radius, gear tooth cutters etc obviously take a higher feed rate just to prevent those cutting teeth from rubbing. Work harden the surface with some materials due to a guessed at feed error, and your going to start destroying those expensive tool tips and maybe turn the work piece into unusable scrap real quick. https://www.harveyperformance.com/in-the-loupe/avoid-work-hardening/ And even if the material doesn’t work harden, that rubbing instead of cutting starts to degrade the tools sharpness and it’s life span much quicker. For what a lot of us could be doing, the cutting tools or end mills might start to get quite small in diameter or cross section. As the tool size or it’s rigidity goes down, the more likely I am to calculate what the proper feed rate should be just to prevent possible tool breakage, too conservative or excess loading. It didn’t take too many broken or shortened life cutting tools before I figured out that a calculator was pretty useful.

An example of how important it might be, that feed rate would also be one of the parameters that wouldn’t be optional to enter into the program with cnc, and that would be necessary for every different tool change and each axis depending on which is being used. For manual mills and once you have some of that experience, then exactly what Chris just said, it’s then a lot easier to make those educated guess’s. Even some of the better dro’s today also have the capability of displaying the table feed rate very accurately during the cutting loads or with any other variables such as very heavy or small and light work pieces. If that information wasn’t of any real use, they certainly wouldn’t bother adding that to those more expensive dro’s. Since getting mine, I now wouldn’t choose to buy any other dro that didn’t have it. Yes it can still be calculated, but these dro’s do it in real time and as the tool is cutting. Maybe it’s a bit less important when the table is geared to the spindle rpm like my little Atlas. But with these add on power feed units, I think it’s something that’s well worth the higher price.

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