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Member postings for Ketan Swali

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

Thread: Home Workshop Site
21/08/2019 10:28:21

Thank you everyone,

All the kind messages will be relayed to him.

Ketan.

19/08/2019 16:39:23

Many on here are aware that Adam Stevenson (son of late John Stevenson) runs the homeworkshop.org.uk site.

Unfortunately, Adam was admitted to hospital on 4th August. Although at present I am unable to go into detail, he is likely to be in the hospital for the next three to four weeks. So, the homeworkshop site is not being updated at present.

If any members on this forum are members on other forums where the subject of inactivity of the Homeworkshop.org.uk site is raised, please feel free to share this information.

If there is any update, I will post on here.

Ketan at ARC.

 

Edited By Ketan Swali on 19/08/2019 16:40:25

Thread: New Milling Machine
13/08/2019 16:03:41
Posted by David Watson 3 on 13/08/2019 15:44:19:

The matter of DRO,s is seemed a good idea at the time. I now start to think are they really something I need.?.

Have a read of Ron Ladens experiences on this thread.

Ketan at ARC.

13/08/2019 15:12:07

Hi David,

The WM14 may complement the size of the mini-lathe. In terms of physical size, spindle taper, and power, it is totally different from an SX2.7. The SX2.7 would compliment an SC4 lathe, which is bigger than a mini-lathe.

WM14 - Spindle taper MT2, INPUT POWER 500w

SX2.7 - Spindle taper R8, OUTPUT POWER 750w - brushless DC motor, physically bigger than a WM14

If metric or imperial is an issue for you, you are best off considering an imperial machine, if you are inclined to think in imperial measures.

If you want to see the physical size, you are welcome to visit ARC and have a look.

Ketan at ARC.

 

Edited By Ketan Swali on 13/08/2019 15:14:10

Thread: R8 spindle advice required
29/07/2019 08:21:33

After reading Neil Lickfords post, and combining with a niggle I had about point 3 of my earlier post, I realised that I needed to correct myself...

As Neil Lickford said, the pin is a location pin, rather than a shear pin. The fact that it could shear if a tool jammed is just an event which can take place, rather than it being a fail safe shear pin. My apologies for creating this misunderstanding.

Ketan at ARC.

28/07/2019 19:42:41
Posted by old mart on 28/07/2019 17:53:31:

I notice that Pete Rimmer mentions that John Stevenson did not include the pin when he made the custom R8 spindle. It's a great pity that John is no longer with us to explain why, he was a great engineer.

There were a few reasons why JS did not include the pin...

1. Depending on who you got the R8 collet from, the slot width and depth could be different. This issue has been debated over time. The obvious issue being.. will the pin in the spindle allow the R8 collet to fit. If not, some modification needed to be made to the pin or the collet. All of this had been experienced by him, us and others over the years.

2. In certain mills, depending on 'the event' of how and when the pin sheared, the back part of the pin could fall inside the spindle assembly and get lodged into a moving part such as the bearing, and in-turn create further damage.

3. According to John, the original Bridgeport R8 design with a slot was designed as such, to be a fail safe. The pin could/should shear as a fail safe to avoid damage to other parts of the spindle assembly, if a heavy duty cut jammed, for example, and allow the collet to slip.

JS came across quite a few 'Bligeports'/clones over the years, many of which no longer had they original pins.. possibly sheared/breaking as a result of impatience by the user when introducing an R8 tool into the spindle.

It is true also as per MichaelGs observations that in such an event, sometimes the whole assembly could still go tight, making it more difficult to take R8 tooling out... although we have not seen this happen too often.. thankfully.

Ketan at ARC.

Edited By Ketan Swali on 28/07/2019 19:44:29

Thread: ARC NCIH Part Off Blade
25/07/2019 17:32:34

Emgee,

This is what the Sumitomo insert removal tool looks like:

sumi insert remover.jpg

sumi insert remover how to use.jpg

Thread: Advice for a mini milling machine
24/07/2019 08:49:38

Generally, now days we say... use the machine as it comes out of the box. Make small adjustments and changes to the machines, if required, to meet your specific requirements, after using the machine, and based on your ability.

Ketan at ARC.

24/07/2019 08:42:34

Alex,

The SIEG SX1LP reaches 5000rpm, and will happily do the job.

The issue is the user, rather than the machine. If your experience is low, the learning curve for adjusting to 'your specific requirement' will be high. If your budget is low, the same statement applies. This machine, in our opinion is better than it nearest comparable Proxxon, if properly adjusted.

If you are into perceptions of accuracy, go with the Proxxon. Many clock makers do! (meant as an observation rather than an insult). ARC has turned away many potential customers from the horology hobby custom base, even though many new potential buyers have been directed to us by the horological institute. Over the years we have found that their general understanding of engineering is low, expectations and understanding of accuracy for the price, are outside the scope of what ARC is able to offer.

Having said all of the above, we do have experienced clock makers who have various ilk of small SIEG mcahines from X0, SX1L, and SX1LP, who are happy with their purchase. But they have experience and have made adjustments to the machines to meet their specific requirements.

The X0 is discontinued. The SX1L is soon to be discontinued (hence the very low price), as we are concentrating on the brushless machines now. The SX1L will not reach the 4000rpm+. All machines run fine out of the box. Accuracy is directly linked with user expectations and ability.

John Haines's comments are on the right track.

Ketan at ARC.

Thread: ARC NCIH Part Off Blade
24/07/2019 07:50:10
Posted by XD 351 on 24/07/2019 04:25:04:

I destroyed a few insert blades doing some testing in the thread linked below but i did find some interesting things out about parting off . I was using the hare and forbes units ( toolmaster ) but i won’t be forking out that amount of cash for a new blade anytime soon - not from them anyway ! I believe Ausee are linked to ARC in some way ? If so i may try their holders and tips .

**LINK**

Just spoke with Steven at AUSEE. His parting off blades and inserts come from the same place as ours.

Just like inserts, there are several grades of holders. ARC has tested holders from various sources from Japan, India and China, and settled on one specific maker from China.

Generally, there are good and bad makers of the 'black finish' ones. The black finish ones are usually more brittle (That in itself does not mean it is bad).These usually snap when there is failure. The 'bad' factory imitations are of seriously poor quality.

The Sumitomo ones are black finish, made from a form of spring steel. It allows for some give, but has proprietary inserts in the same way as ISCAR. So, the GTNs don't fit it. Price of Sumitomo holders are high, and more suitable for high production environment. I am guessing that the ISCAR one is in similar range.

So, as a result, ARC settled on the factory we use. The brown finish holders which ARC and AUSEE sell are made from (Chinese spec.) GB 60SI2MN Steel - a high quality alloy spring steel. It costs more than the general 'black finish' stuff. It does not mean that it is better or worse than the black holder. it just has 'more give' before bending or snapping, falling more in line with the Sumitomo idea, without the big cost.

Just like the black holders, there are very cheap brown finish holders, which are poor imitations, not made from the grade of steel specified above. But if they suit the users purpose in the hobby environment, and it works, the user is non the wiser. Some sellers using the auction platform state that their holder is made from a specific grade of steel. But how is the user going to check?, and does he really know, understand or care if it works for him/her?. There is nothing wrong with that, but 'with respect' when they talk about it in YouTube videos or on forums, how much do they really know about it? How much is true, false, money laundering?

Ketan at ARC.

24/07/2019 06:45:46
Posted by Blue Heeler on 24/07/2019 01:58:37:
Posted by Hollowpoint on 23/07/2019 18:21:39:
 

Why not just swap the tips? The ones in the link look an awful lot like gtn3 tips. These are readily available and if you are prepared to wait they can be had for as little as 60p a tip from China.

 

Worth a shot to buy and see, though I'm thinking that the Iscar would be a proprietary pattern.

After reading the problems that people have with parting off, I'm thinking of just staying with the Iscar holder and tips. Even though they are expensive, I've never had the slightest problem parting anything with the Sieg C6 lathe and the Iscar holder and tips, honestly its like using a hot knife through butter.

If you are happy with the ISCAR holder, I would suggest that you consider the ISCAR inserts. The GTN2s or 3 will not fit the ISCAR holder.

There are various qualities and grades of GTN2s and 3s available. Even though ARC sells Chinese origin, we are particular about our sourcing for inserts, and we pay a lot more for them, than 60p each. If the user is happy with the 60p investment, and it works for him/her, that is well and good, too.

Ketan at ARC.

Edited By Ketan Swali on 24/07/2019 06:46:48

24/07/2019 06:37:25
Posted by Emgee on 23/07/2019 22:22:43:

Does anyone have a picture of the GTN insert removing tool, or a short description. ?

Emgee

It looks like a bent flat head screw driver:

gtn2 removal tool1.jpggtn2 removal tool2.jpg

Ketan at ARC.

23/07/2019 06:38:25

Hi Jim,

This product and similar have been discussed on here and more recently on MEM. I cant find the links at present.

As a summery, it is a bit like marmite. You either like it, get on with it and are happy, or the exact opposite. I personally happen to prefer the HSS Co8 type...which is also thinner than the carbide offering, at 1.5mm or 2mm. My reasons are down to fear.

In the 'likeit' camp are people like Smithy from MEM, our Neil Wyatt, the late Sir John and many others.

The main issues are - not so good for beginners, and as you have to run the machine relatively fast, the fear is there during parting, combined with rigidity issue around the machine components, combined with constant positive feed required for parting. The carbide blade/holder is not forgiving, and can break more easily if confidence levels are low. Great and easy to use for non-ferrous, but a lot of caution, skill and confidence required when using it on steel or cast iron.

For every five buyers, three get on with the NCIH type, one plays with it with some fear, and one breaks it. Most beginners WILL most likely break it.

Ketan at ARC

 

edited to correct spellings,... not had coffee yet.

Edited By Ketan Swali on 23/07/2019 06:40:02

Thread: Warco Mini Lathe
23/06/2019 08:13:16
Posted by Peter Russell 4 on 22/06/2019

The reason I have discovered for the worst part of the rocking and I hang my head in shame is because I fitted a DRO sensor and thought wrongly I had it clear of the bed now that has been removed its better but not good so its a new saddle from ARC for £19 ish as there is a bow in it where the clamp plate goes.

Once I have this I will update.

Many thanks to all who responded.

Hi Peter,

just read this. I would suggest that if you want a new saddle, consider buying it from Warco as the SIEG saddles are designed for SIEG machines, and probability of them fitting your machine are low. Also, things like these are not retro fit and probably will require some scraping, even after you get a saddle from Warco.

Ketan at ARC

Thread: spindle bearings
17/06/2019 12:31:54
Posted by RMA on 17/06/2019 08:36:45:

Yes I would generally agree with that, but the OP suggested two options including changing to tapers. Personally, if I was going to use the machine a lot and hard, I would change to tapers if the castings allowed for the mod.

Cost is another concern the OP has, but again it depends what the machine will be used for.

I understand, and after re-reading the OP, I also get where you are coming from. In that respect, you are right.

So, I need to clarify my earlier position. This is my opinion... Most machine designers have taken various factors into consideration, and reached a balance/compromise for the type of bearings they have used in the spindle of their machine. For this reason, I have gone along the line of changing like for like... where possible.

So, if one still wants to change the type of bearings which are in their spindle assembly, here are some of the points to consider...

For example, changing from general 'ball raced bearings' to 'angular contact (ball raced) bearings, will allow for a good improvement in accuracy. Similarly, going from angular contact bearings to Taper roller bearings will give a further improvement in accuracy.

The pre-load on bearings is one of the factors. All other things being equal, if you change from ball raced bearings to angular contact bearings, the max speed will reduce based on contact angle and pre-load, and the max speed will further reduce if you change to taper roller bearings, mainly due to the surface area of the rollers in contact with the inner ring, and how much pre-load is applied.

Another factor is the electronics. If changing from one type of bearing to another, one needs to consider the following: With more pre-load facility available for Angular contact bearings, the motor 'may' have to work harder to turn the spindle, and it may have to work even harder for taper roller bearings. The question then arises, is the motor up to it?, is the belt drive or gear train up to it? So, one has to consider the balance of pre-load to motor load to forces on the gear train/belt drive, to get the accuracy required. Are the electronics up to it?

Another factor is heat generation.. are the new bearings lubricated correctly with the right type of grease?, and is the quantity of grease put inside the bearings correct (usually roughly less than 20% of internal volume of the bearing). If this is correct, how will the pre-load on such assembly behave in terms of heat generation, if you change from Angular Contact bearings to taper roller bearings (TRB), when running the spindle at 6000 rpm?, combined with the load on the motor... correct running in procedure - short term high heat generation before settlement, etc...

In our experience, going from ball raced bearings to angular contact bearings is a reasonable change one may wish to consider. However, going from ball raced bearings, or angular contact ball raced bearings to TRB, especially where higher speeds are involved, is something one should be more careful about, keeping in mind the points raised above. For manual hobby machines upto 3000 rpm, this may be a small issue.... subject to control board overload protection/or not.

There are various other points, relating to the cutting tools used before and after such changes, and their effects on the tool - HSS or Carbide (which need higher speeds). As carbide seems to be a new fashion thing, reduction in speed could have deferent effects on the cutter, as well as the results.

So, really up to the person making the change to consider many factors before making a change.

You also made a good point with reference to TRB: 'if the castings allowed for the mod' and/or the inner spindle assembly allowed for it.

These are just observations ( I am not trying to create an argument). teeth 2

Ketan at ARC.

16/06/2019 17:39:03

There are various issues on this thread which are open to confusion..

1. Generally, bearings should be replaced like for like. i.e. angular contact bearings to be replaced with angular contact bearings. Taper roller bearings to be replaced with taper roller bearings and so on.

2. The OP has a manual Chester machine with maximum speed upto around 3000 rpm. The SIEG KX3 CNC... depending on vintage had a maximum speed of around 3500rpm in the early years and the newer versions I think around 5000 ~ 6000 rpm. The bearings in the SIEG KX3 CNC spindle assembly (size and type) have also changed over time.

With manual machines, in place of higher precision bearings, due to low maximum speed, you can probably get away with using general purpose like for like type and size replacement bearings for hobby use, until you start considering bigger industrial machines.

The SIEG KX3 CNCs have always been fitted with higher precision bearings. Where match pair angular contact ball bearings are fitted, they should be replaced with equivalent size/type match pair angular contact ball bearings. This also helps to get better runout accuracy. If one doesn't use match pairs in such cases, the accuracy can be open to question. It will still work, depending on if the user is happy with the result achieved after replacement.

pm sent to Michael.

Ketan at ARC.

Thread: Hostaform, Nylon or Steel For Mini Mill Gear?
29/05/2019 15:10:52
Posted by colin hawes on 29/05/2019 14:59:56:

Does the control board have no overcurrent / overload protection then? Just a question . Colin

Depends on the machine. The lowest spec. mini-lathes don't have. Also, on such mini-lathes, and even on high/low geared mini-lathes which have an overload protection, there is a 'user' element to be taken into consideration. If a new user, then failure - damage is related to how the stoppage occurred - heavy handed due to incorrect/improper/inexperience use?... in which case, probability of gear breakage (nylon) or board failure or both, could be equal. If metal gears + entry level electronics + new inexperienced user, then board failure event probabilities increase. There is no clear reason. Just probabilities related to user.

Ketan at ARC.

29/05/2019 14:40:51
Posted by colin hawes on 29/05/2019 14:26:49:

I have always reckoned that gears should be unbreakable not fail safe and that plastic of any sort for this job is used because it is far cheaper to injection mould a plastic gear than to machine a steel one.

I understand Colin,... in which case... probability of electronics - board giving up the smoke can increase, and we are happy to sell more expensive components such as control boards... angel

Ketan at ARC.

29/05/2019 11:05:49
Posted by William Chitham on 29/05/2019 10:49:17:

Thanks Dave, found it., ordered it. I noticed they also do steel replacements for the high low gearbox gears, have you fitted those? I wasn't planning to make a replacement for this although ironically I bought the mill with a view to making metric-imperial conversion gears for my lathe.

William.

William,

Unless you really need want them, it is better to stick with the nylon gears - which act at a fail safe. Also, the high/low gears are cast iron. They will make your lathe more noisy. There are users who still want them, so we sell them for the old geared C2/C3 metalworker mini-lathes. If you still want them, consider the bigger one to be metal and the smaller one to be nylon which may still build in a small amount of fail safe.... although I am aware that this combination suggestion is questionable with certain people.... but it also works.

Ketan at ARC.

Thread: Mini-Lathe setup for an absolute beginner?
21/05/2019 16:58:31
Posted by James Bennet 1 on 21/05/2019 16:38:12:

> Ketan at ARC.

It's really nice to see sellers engaging with the community here. Excellent customer service! I will be in touch in 3 weeks once I get paid, to place an order

No worries James. Before making your purchase, If you call and speak with Ian, he will be able to answer all your questions for you.

Ketan at ARC.

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