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Member postings for Sarah

Here is a list of all the postings Sarah has made in our forums. Click on a thread name to jump to the thread.

Thread: Further Adventures with the Sieg KX3 & KX1
16/04/2020 17:11:17

Very impressive Jason 😊

13/04/2020 17:55:02

Hi Barrie,

Thanks for your post on milling carbon fibre, I've sent you a message with a few questions.



13/04/2020 16:36:21

Hi Adam

All done 😊

Thanks again for your help. Spindle speeds are quite close to demanded speeds and I've spent the afternoon practicing some bits in foam before I cut in aluminium.



13/04/2020 12:32:48
Posted by Adam Stevenson on 12/04/2020 13:13:25:

It was found to be 350 for best results, the velocity is the one important for the spindle. Lots of testing was done with these machines and each one from Arceuro was calibrated to allow a quicker setup by the users.

The actual values are regardless it is the ratio between them that matters. Think that for each 360º the computer sends steps, it is not just how many steps are sent but how fast the amount are sent too. But we are not sending steps but a Voltage that the controller uses to drive the motor at a set speed, they is also a in-built tacho that will increase or decrease the current to keep the speed constance. So at the end it is not the number of steps sent per revolution but the rate at which they are sent. So we pick a nice number and then how fast we send them and balance the ratio between them, in this case 350 x 4,000 or 35 x 40,000 or 3,500 x 400. The computer will have limits so we picked the mid ground that most PC's would work with.

Edited By Adam Stevenson on 12/04/2020 13:16:52

Hi Adam, I now understand what you meant about the ratios of Step per and Velocity.

Your 'Step per' multiplied by 'Velocity' figures are approximately double those of mine. I put your Step per x Velocity in to my machine and the sure enough the rpm doubled! A requested 2000rpm shot up to over 4000rpm! So presumably I can either have my 100 x 6000 or modify yours to 350 x 2000 (plus a bit of twaekage). Is there any practical difference between the two?

The X, Y and Z axis seem fine at 5us Step Pulse, they just sound a bit different.

Thanks for your help and patience.



Edited By Sarah on 13/04/2020 12:40:40

12/04/2020 16:26:01

Hi Adam,

Thank you so much for your help 😊 I'll spend a bit of time tomorrow putting in your values and fine tuning to get the Spindle rpm matching rpm requested. I understand whay you said about ratios of Step per and Velocity, but still can't rationalise the big variance in the different machine's values, however as long as it works 😊

Still waiting for the new 6mm cutters, I've got 4 flute cutters, but I'll be patient and wait. Many project's to do lincluding trying to machine some 2mm carbon fibre sheet.

Thanks again,


12/04/2020 12:13:13

Hi Adam,

What effect does varying the Steps per value? I can understand it's use with stepper motors, but not with a brushless motor.



12/04/2020 10:23:58
Posted by JasonB on 12/04/2020 10:10:52:

Sarah, going by what Adam (Son of the late John Stevenson) said both mine and Ian's are connected by USB so our speeds are controlled differently to your earlier parallel port machine which is why I have nothing on the spindle screen and would think Ian's would be the same though he only showed the X axis..

Hi Jason,

I think Adam said the timing was controlled differently, but are the Steps Per, Velocity and Acceleration still adjustable from the Motor Tuning screen? I've been doing a lot of reading on line but not found enough out unfortunately.

I've got a friend getting me some aluminium offcuts from work which will be very useful for mounting bit to 😊



12/04/2020 09:37:33

Hi Guys,

Thank you for the photographs of your spindle settings, your figures are very different to each others and also to mine as well. I've added a photo of mine below. The three machines are:

Steps per.      Velocity.       Acceleration

1.                     120.               4

500.                 1000.2.        100

100.                 6000.            500


A few questions for you if you don't mind.

I understand what 'Steps per' do on the X, Y, Z axis relating to the stepper motors and ball screw drives, but what does it do on the Spindle Speed and why are our three machines so different?


Why are the Velocity and Acceleration figures also so different for the three machines?


I removed Mach3 and the Sieg setup files from my PC, then installed them again to make sure I had the default setting. If I go into the Motor Tuning screen, don't change anything and exit by just closing the X on the top right of the screen the Step Pulse won't change from 4us. However if I go into the Motor Tuning screen and click on the OK button to leave the screen, then when I go back into the Motor Tuning screen again it has changed to 3us. It will retain a value of 3us and 5 us.

When it does change the Step Pulse to 3us, or a value of 5us, this changes the value for the X, Y and Z axis as well and changes how the axis are driven. Will driving the X, Y and Z axis at 5us cause any problems?


I can match the measured and demanded spindle speeds if I do change the Step Pulse to 5us, but I'm wary of changing bits I don't really understand.


Thanks for the video's and pictures of your work on your machining, giving me a good idea of what to do. I'll post some of mine soon hopefully.  I wouldn't have thought of fixing a bit to be machines to the side of a chunk of aluminium, it will make a bit I need to machine a lot easier thanks.


I appreciate your help, hope I'm not asking too many questions, I'm just eager to learn.


Best wishes,





Edited By Sarah on 12/04/2020 09:38:58

Edited By Sarah on 12/04/2020 09:41:50

09/04/2020 19:37:30
Posted by Ian Johnson 1 on 09/04/2020 19:34:56:
Posted by Sarah on 09/04/2020 17:46:59:

Hi Ian,

Would you be able to let me have your settings please 😊

The pulse settings changed them selves from 4us to 3us after I increased the velocity, which then put the speed back down. Jus coildnt get them to change back to 4us.


Edited By Sarah on 09/04/2020 17:47:44

Yes I'll have a look for you Sarah probably tomorrow because I've got a virtual pub quiz to take part in tonight!

I hope you enjoy your virtual pub quiz, I hope the beer is not virtual 😉

Best wishes,


09/04/2020 19:32:28

Hi Adam,

Thank you for typing all that in 😊 That's the procedure that I used, worked fine as I increased the Velocity value until it was within 10 rpm, then I pressed the Save Axis Settings and Okay. Back at the main screen I types in the speed required and it sounded a bit slow again. I tacho'ed it again and the speed had dropped. When I checked the Motor Tuning and Setup screen it had retained my new Velocity figure, but the Step Pulse had dropped from 4 to 3us. Changing it to 4 brought the speed back up, but whenever I left that screen it reverted to 3us. Got quite frustrated!

I don't know if I need to alter the Steps per parameter?



09/04/2020 17:46:59

Hi Ian,

Would you be able to let me have your settings please 😊

The pulse settings changed them selves from 4us to 3us after I increased the velocity, which then put the speed back down. Jus coildnt get them to change back to 4us.



Edited By Sarah on 09/04/2020 17:47:44

09/04/2020 15:40:54

i was surprised as well that the speeds are that far out. I did think it was simple, I just changed the Velocity value from 6000 to 7800 and it was just right. It just wouldn't retain the pulse width value, I tried saving the values in slightly different ways but I couldn't get the pulse width to stay at 4us. I did wonder if the difference in velocity values was responsible?

I didn't hit the over ride, just double checked anyway.  I would be grateful for your Mach3 settings.



Edited By Sarah on 09/04/2020 15:57:56

09/04/2020 15:07:18


I have had a break of a few years using my KX1 mill and one job I wanted to do last time I used it was to check the spindle speed, I always thought it was on the low side. As I'm waiting for some new cutters I did a spindle speed test and got the following results. I did check the tachometer on a couple of other machines and it seems quite accurate.

Requested RPM Actual RPM

1000 831
2000 1721
3000 2573
4000 3422
5000 4318
6000 5223
7000 6007

I was surprised it was that far out. I found an article on KX1 motor tuning and tried to adjust the spindle motor movement profile. I increased the Velocity and was pleased when I achieved 7,000rpm within 50rpm. I saved the axis settings, pressed okay and went back to the normal display. Unfortunately next time I selected a spindle speed it had dropped again. I checked the spindle motor movement profile again, it had retained the new Velocity figures but the Step Pulse had changed from 4us to 3us. though I tried quite a few things I cant get Mach3 to retain the Step Pulse figure. The setting were: Steps per: 100, Velocity 6000 (changed to 7800), Acceleration: 500, G's: 0.050988, Step Pulse 4 (system changed to 3).

Has anyone else changed the spindle speed ? There are a few variables on the Motor Tuning page, but I dont know what they really do and I'm reluctant to change things that I don't understand in case I damage anything.

i would again be grateful for any help.

Many thanks,


Thread: Milling a profile - help with technique please
08/04/2020 16:26:01

I watched the videos and I will be happy if I can get a finish like that.😊

I've made use of the offer at Cutwell (buy 2 get 1 free) and bought three of the 6mm cutters you recommended. I look forward to trying them.

I've got my workshop vacuum cleaner, so I'll use that to clear the swarf. I've got a few chunks of surplus aluminium so I'll mill some flat and use that instead of MDF. I'm very good at using my safety glasses, the last pair were damaged when a Dremel cut wheel broke up and a bit hit the lense!

Many thanks again for your help.

08/04/2020 10:25:37

Thank you for your replies, I do appreciate your advice.

I have ordered some 6mm cutters and I will modify my Cut2D files for a 6mm dia. cutter doing a roughing and a finer finishing pass, using the feed parameters which you have advised.

As I have four identical parts to make for the first part I will slot around the profile, then for the second part I will cut some material nearly to size, screw it to some MDF and then mill from the outside inwards, with again having a final full depth finishing pass. The next two I can vary feeds to see how it effects the finish. I do need the tight 1.5mm radius on two points, so I will do that as a seperate operation after completing the profiling with the 6mm cutter. I am using WD40 as a coolant/lubricant, is that okay to use?

I will also get some specifc grade of aluminium, as the stuff I have is just something I got from ebay and I think it is on the softer side. I'll have a read up on aluminium material specs.

Thanks again for your help.

Regards, Sarah

07/04/2020 18:56:19

I've just got back to machining a few bits after a break of a few years and I would appreciate a bit of advice from those with more experience than myself.

One of my projects involved CNC Milling the part out which is in the attached photograph. My feeds and speeds were a bit on the industrial side (1.25mm doc, 80mm/min feed rate, 6,000rpm with a 2 flute 3mm slot drill, cutting 5mm deep in aluminium) for my KX1 mill as it did vibrate noticeably. I'll reduce the depth of cut and feed rate a little for the next try.


My question related to slot milling, when I cut out in similiar profiles in aluminium, what would an appropriate cutter size be? Also would I be better cutting the slot width in more than one pass, i.e. cutting further out and then an finishing pass to bring the profile to size. The cut finish with cutting the 3mm slot with a 3mm slot drill was very poor.


I'd appreciate any advice please, thanks 😊




Edited By Sarah on 07/04/2020 18:57:15

Thread: Which Stuart engine is this
16/11/2012 13:14:50

Hi Ian,

i know you are going with the Keyway, but just for information the new Stuart No.1's have gone from a Keyway to a grub screw. The crankshaft diameter has been reduced where the flywheel fits, this allows the flywheel to butt up against the larger diameter on the crankshaft. The grub screw fitting in at an angle not only stops the flywheel from rotating on the shaft, it holds it snug against the increase in diameter of the crankshaft.

I presume that if there isn't a change in diameter on the crankshaft then the keyway is the better way to go.



Thread: Midlands Model Eng show v Sandown
20/10/2012 21:48:33

We went to the show on Friday and enjoyed it a lot. It wasn't too crowded and the exhibitors were friendly and I picked up a few useful tools. It was also nice to see Stuart Models there and that they are producing more models in there range. We will be back next year.


Thread: Which Stuart engine is this
20/10/2012 17:36:23

Hi Ian,

You mentioned in another post 'Casting defect In cylinder wall' that your piston had a groove which would take two 1/8" thick piston rings, one on top of each other. I have just seen an old and very new Stuart No.1 piston and rings. The old piston had two piston rings on top of each other, like your No.9, but the new No.1 has two seperate piston rings with a 1/8" gap between them. I'm not sure why the piston ring configuration has changed, but it might be worthwhile considering the alternative configuration for yours.



Thread: Casting defect in cylinder wall
20/10/2012 17:12:16

Hi Richard and Neil,

Thank you both for the book recommendations, I'll have a look out for both of those. I have a couple of projects where I need to make some plugs with interference fits and I do need to do some research before I do this. I also want to find out dimensionally what is a good fit for crankshafts into brass bearing blocks. The No.4 engine does have too much play between round the bearing blocks and it would be nice to make the new bearing blocks to a specific size rather than just machine a bit then check, machine a bit then check etc.

I am learning a lot with the steam engines, but still a lot more go

Many thanks for your help again,


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