Member postings for Ketan Swali

Update for Kenneth and other EU customers (27 states):

On 12th February we updated our site to deal with EU customers, be it IOSS or above duties and taxes paid to destination country.

All prices have been quoted for EU customers in Euros for a while now. However, from 12th February, all handling, courier/carriage, destination country duties/taxes to the 27 EU states will be added and collected at the checkout. This is to make sure that such order reach EU customers faster as all customs formalities and payments will be completed by us in advance on EU customers behalf.

We are aware that such costs for low value orders are still high. We are regularly reviewing this with our carriers with hope that the logistical costs for low value orders could reduce over time.

This procedure will be applied to all EU orders, EXCLUDING orders for machines which weigh over 70kgs., and EXCLUDING business to business (B2B) orders. Updated terms can be found here on our site.

https://www.arceurotrade.co.uk/projects/Info/eu-terms-2022.html

Quite a few orders have come through post change, and we are happy with the initial response from EU customers. Thank you for your custom.

Ketan at ARC

If you are prepared to take the risk to do following test: how easy or difficult it is to stop the motor by hand (wearing appropriate leather gaunlets) at slow to medium speed.?

If difficult to stop, then issue may be mechanical.

Have you checked connecting pulleys to see if any have worm by the keyway?

Ketan at ARC

In addition to checks and suggestions made by various people, you may need to check the pre-load you have put on the bearings.... check how easy or difficult it is to turn your chuck by hand. It there is too much re-load, it will be difficult to turn the chuck, meaning that there is more power is required/drawn... which can result in certain components blowing.

ARC doesn't sell any KB control boards.

Ketan at ARC

Hey Michael,

I didn’t take your post to be confrontational at all.

I know you are trying to help. I was just playing through the possibility of angular mis-alignment.

Ketan at ARC

Agreed Michael.

• At present, I am only presuming that an Oldham coupling is fitted.
• if an Oldham coupling was fitted, then the probability of angular mis-alignment during assembly installation were/are low.
• It has lasted over ten years without issue. An event which could cause angular mis-alignment would have been some kind of hard shock, which could bend motor shaft/ball screw shaft, or more likely break/damage the acetal disc.
• the reason why HUCO Oldham coupling were requested and supplied by ARC to the factory at the time was that these were preferred by us over flexi coupling which the factory used on all other machines. In original tests, we found that a mis-alignment issue caused the end of the ball screw to snap due to the force/strain placed on it with flexi coupling. In addition, the movement got strained, leading to inaccurate cuts being made, for example when cutting a circle. The extra strain would cause a defect in the cut… failing to cut a proper circle in certain cases where flexi coupling was used. This has been seen on several hobby CNC machines, including a well known ‘American’ hobby CNC machine, presented as problem on a negative YT video, without anyone really realising that strain put on a ball screw by a flexi coupling was the real cause of an inaccurate circle cut.

At present I am only trying to help Mick to check and deal with obvious mechanical issues which I can remember about.

Mick says that he is unable to stop the motor with his hand, so this suggests that there is more than enough torque coming off the motor…. much more than hand turning the ball screw. For this reason, I suggested to look at the acetal disc.

Ketan at ARC

Apologies, I failed to properly understand what Adam said.

If you were unable to stop the motor by your hand, then issue maybe mechanical.

Between the motor and the ball screw is the Oldham coupling with an acetal disc in-between the couplers. Here is how the assembly works: link

is the disc worn?. Technical details of the disc can be found here: link

Ketan at ARC

I think I understand and agree. It may be possible that the acetyl disc could have worn over time, and or it maybe catching.

Also, when the stepper motor was disconnected from the ball screw and if was free running okay without being coupled to the screw, how easy was it to stop it by hand?

Ketan at ARC

Looks good and clean.

Oldham couplings (not flexi-couplings) are designed to deal with mis-alignment, and do not introduce any stress on the motor or the ball screw. Usually they do not need lubrication. There is an acetyl disc in between the couplers.

Difficult to figure out what mechanical issue is causing the bind.

Ketan at ARC.

From the KX1 Manual put together by John Stevenson, Adam Stevenson and Alan Simmonds in 2008:

X & Y axis 1.35 Nm each, Z axis 2.2 Nm

• the KX1 machine which Adam Stevenson currently has, has different drivers, breakout and control board from the ones used in 2008/2009.
• The user may need to look at all the electrical connections to confirm non have become loose over time, or become loose due to some adverse event.
• Check the connections and operations of the micro switches,
• check if the ball screw has not got contaminated, but to remove the screw and nut from the screw a specific procedure needs to be followed to avoid balls falling out of the nut- see You Tube videos (50% good/50% crap). Just winding by hand from the end does not prove that the ball screw is okay. contamination/swarf can move randomly, an observation which has been made in the past.
• the existing stepper motors as they stand (if they have not developed a fault) have enough torque to run the axis in question. To check if it is faulty/cause of the bind, one needs to disconnect it from the axis ball screw which is effected. (As I did not get involved in this dismantling process, I cannot guide.). Once disconnected from the ball screw, run it to see if it is okay. The stepper motor should/will be connected to the ball screw with an oldham coupling and/or similar. Most KXs made for supply through ARC at the time had be requested with such couplings.

I am unable to assist or advise on dismantling, re-assembling, electronics, computers or software.

Some electrical components are still available, without guarantee or warranty.

Ketan at ARC

Edited By Ketan Swali on 30/01/2022 13:32:59

Edited By Ketan Swali on 30/01/2022 13:36:31

Hi John - modeng2000 and all,

This is an observation, rather than a criticism. I am not looking to offend anyone.

This morning, we had a call from a customer who had the same machine from the same supplier, with a blown control board. He too has a replacement machine coming from Vevor. He also purchased tooling from them which he believes to be of poor quality.

As a result of his experience, his general opinion of 'mini-lathes and tooling' from China was that they are all of poor quality. We helped him understand the tooling he had purchased and we helped him understand that the mini-lathe he purchased was totally different to what is sold by reputable U.K. sellers.

Buying machines and related products from eBay, Amazon or Vevor, from unregulated foreign entities come with their own set of issues - good, bad and ugly.

I can understand that the purchase is made because the machine and tooling was cheap. However, the only buyers who should take such risks are those who know what to expect for the price, and be happy to be able to fix it if things go wrong.

Sadly, a high percentage of buyers who buy such cheap machines have very low engineering knowledge or experience. If it is right or wrong to go down this road, is really up to the buyer.

However, it is concerning if people get put off the hobby based on this experience, and it is wrong for all reputable sellers to be tarred with the brush of 'all Chinese mini-lathes and related products' are rubbish.

In the case of the person who called us, he purchased some tooling from us. In his case, according to him, he will get the replacement machine, and then off-load a working machine on eBay... probably for someone else to experience. Then he will purchase a new mini-lathe from us.

For ARC, there is a silver lining.. We get calls as per above example, every few days. Many turn into new customers, to whom we sell mechanical spares, and new tooling, or new machines. They then turn into regular customers. Unfortunately, in all cases we cannot help them with the electronics...control board replacement, as they are totally different to those fitted in SIEG made mini-lathes.

So John and all.. If you really know what you are doing with a cheap purchase, ....please don't feel guilty for accepting a new replacement machine from Vevor or any other unregulated foreign operator off eBay, Amazon or elsewhere. The more such operators are hit financially for their incompetence, the more they will realise that it is not an easy revenue stream.

However, it is difficult to say how many NEW people have been put off the hobby resulting from their experience.

Ketan at ARC

Link: Joint Square Edge Needle Files

It was discussed on this forum in 2018: Link

Link: Joint Round Edge Needle Files

Ketan at ARC

Edited By Ketan Swali on 26/01/2022 17:51:13

Ahh I see. I am familiar with the JT/B taper being a part of the spindle, where the wedges become essential... as is the case in a SIEG X0 mill.

As I am not too familiar with drilling machine spindles, I failed to take that thought into consideration.

Thank you Rod... learned something new (to me) today.

Ketan at ARC

The reason why we had different wedges in our workshop was for the purpose checking different chucks on arbors.

Question for those who may know: In normal use environment, why would people need these wedge/s?, unless the JT/B taper is a permanent part of the spindle, or the wedge/s are being used in a muti-tool type assembly... such as the one used in a multi-purpose live centre set.

I mean, once the chuck and arbor are assembled correctly, why should there be a need to take the assembly apart?. If the chuck becomes faulty over time, it should be cheap enough nowadays to buy both the chuck and arbor NEW, doing away with any damage when taking the assembly apart.

Ketan at ARC

The Jacobs style 'thin wedges' are sold and used in pairs.

I have observed the thick Albrecht ones being used as singles as well as pairs. Although it feels better for the Albrecht ones (or any other) to be used as pairs, sometimes these wedges are too thick at the slimmest part to fit into the gap in between the chuck and the arbor. I guess it depends on the application.

Many moons ago we purchased the Albrecht ones for use in our own workshop (now mothballed) in singles rather than pairs. We also used pairs of the jacobs slim style, and we made a few of our own... all depending on application.

We stopped selling the slim wedges a couple of years ago after the maker closed down.

Ketan at ARC

Here are some rough and ready pictures:

This picture is same as the keyless chuck you purchased, hand assembled:

Rough measurement of the gap:

Measurement of the gap after hitting (shocking) the arbor into the chuck with blow hammer... not ideal method, but just done for the purpose of these pictures:

Overall picture of an Albrecht chuck removal wedge:

Close-up:

Albrecht chuck removal wedge in gap. The assemble is usually held in the mill, and a sharp blow with a blow hammer is used to separate the mating tapers. Picture just taken to show it in the gap (not usually used at an angle for removal). Usually held at 90 degrees... but good possibility of marking the arbor or the chuck, depending on how long the assembly has been in place.... more difficult to take off after longer period of time..

Forgot to add... thickness of Albrecht wedge:

Ketan at ARC.

Edited By Ketan Swali on 17/01/2022 10:29:51

Hi Roger,

Ian will review your email when he comes in, and he will get back to you.

Just reading this thread (without site of your email), I would suggest that both the chuck and arbor are fine, regardless of expectation for the price in comparison with expensive Rohm or Albrecht chucks.

We sell both products on a daily basis... mainly to industrial users, as well as certain blue chip trade re-sellers, without complaint. We know the factory from where we have purchased the chucks from, and we know the factory from where we have purchased the arbors from. Apart from the odd Friday afternoon product, we are comfortable with the consistency of our supply. However, I will let Ian review your email and get back to you.

With regard to getting into detailed discussion on the subject on here, this is all I will say:

About ten years ago, my team, John Stevenson (who passed away in 2017) and I spent over a year checking keyless chucks from 5 different factories. There are three grades of Chinese keyless chucks. There is high precision - used for CNC (P), Heavy Duty (H), and General (G).

Our findings were as follows:

• Some factories sampling fialed to reach any of the specifications they specified.
• Some factories only offered us G grade.
• Two factories offered us all three grades, and we chose to test the P and H grades only.
• P grade failed all around on the SIEG machines on which we tested them, and we found that the run-out was worse that the H grade.
• We even had a batch of P grade which we returned to the factory as they failed on run-out.
• Tests on our machines included using silvers steel, known turned reference stock, reference stock supplied by the keyless factory for testing, 6mm and 10mm. These were checked at 15mm and 25mm away from where they were held in the chuck. These were checked by hand rotation, as well as at low speed. The chucks were loosened, the stock was moved by hand inside the chuck, so that the jaws could be tightened in a different position. Then the chucks were checked again for run-out. These checks were done on three different machines.
• Results were different on every machine. Variable factors taken into consideration... spindle run-out, distance from end of spindle to the point at which the round stock was checked, arbor fit to the spindle, JT/B taper fit to the keyless chuck, and one or two other elements which I may have forgotten.
• Results on the keyless chuck factories test rigs were also different to the results we were finding when fitted to the SIEG, as well as Johns and certain other peoples machines.
• An average was taken, and we finally settled on the factory we use use, with the H grade. It happens to be the most expensive, but at the same time the smallest factory (in terms of production run), from the five factories we tested.
• It would still be wrong for me to set a reference for comparison against Rohm chuck because:
  • there are too many variables involved as mentioned above
  • we do not buy the arbor with chuck pre-assembled at the factory
  • our results differ from rests on the keyless chuck factories test rig

We are not prepared to purchase and supply chucks pre-assembled with arbors from ANY factory. Reasons are:

a. non of the factories we tested, including the keyless chuck factory we use make their own arbor.

b. the quality/grade of the material used for the arbor in the pre-assembled units can be variable.

c. the accuracy of the material used for the arbor in the pre-assembled units can be variable.

d. the cost of the arbor from the factory where we buy the arbor is more expensive than the cost of the arbor supplied by the keyless chuck factory, and we cannot be certain of the source.

d. we do not want to keep pre-assembled stock of products.... as this would mean we would have to keep more stock.

We have purchased and supplied the same consistent quality of arbors from one specified factory for over 20 years. The return rate is next to zero.

Chuck removal wedges: For jacob style chucks - they are slim wedges. Albrecht wedges are very thick.. I am guessing because some of their chucks may fit with a bigger gap... but I cannot say for sure.

If the tapers have been mated correctly - i.e. male and female cleaned out to remove the transit oil, and press fit correctly/hard enough (and not by hand only), the resulting run-out is considered to be reasonable for the chucks and arbors we sell. Again, it would be wrong for me to get into results of the tests, as well as any detailed discussion on this over this forum, due to all the assembly variables involved.

Also a note: depending on type of use, the keyless chucks can also tighten and jam.. including Rohm/Albrecht or any other keyless chucks. If mail/female tapers were not cleaned before assembly, they will mark the mating tapers and change accuracy. Using hammers to dismount chucks from tapers can also result in the same problem.

This is a matter for Roger to discuss with Ian and conclude.

Ketan at ARC.

I just spoke with Louis Rex. He informed me that regrettably the Doncaster Show is not taking place this year. Their website will be updated with an official statement hopefully by this Sunday.

Ketan at ARC

Congratulations Simon,

From zero knowledge of metalwork, starting this project in 2007?, learning over time from the collective, participating here, and getting to this stage by end of 2021 is a great achievement.

Ketan at ARC.

Hi Frank,

So that people can give their thoughts clearly, could you please clarify if you mean SIEG X2 or SX2?

SIEG X2 is the original brushed motor with gear drive.

SIEG SX2 is the newer brushless motor belt drive.

Ketan at ARC.