Member postings for Jak2g

Thanks John - the basics do no seem very difficult but she of the comments about exploding wheels got me spooked!

Probably just overthinking things...

Hello all

I recently acquired an exe surface grinder and have torn it down for a thorough clean, paint and rebuild. I'm almost at the stage that it will be turned on for the first time (in my possession!).

Whilst I have come a long way learning how to use a mill and lathe, I am slightly hesitant to jump right in to the surface grinder without at first a bit of guidance. I'd love to meet an experienced machinist / tool maker in or around Leeds that could give me a crash course (no pun intended!) On basic use of the surface grinder with an emphasis on safety.

I'm a middle aged hobbyist that would love to learn from someone who actually knows a thing or two. I'd be more than happy to reimburse reasonable cost for time and expenses, etc.

If this could be you, or someone you know, please get in touch with me. I'm located in Leeds nearer to Castleford.

Cheers!

Thank you all for coming back to me. I must admit that I didn't realise any replies had been posted (it usually emails me but not this time!!).

I decided to go for a 220 to 410 VFD. I did try it on my 220 VFD and the motor ran fine, so at least I know the motor should be ok at full speed!

Cheers!

Hello everyone

I've recently began restoring an exe surface grinder. I had anticipated running the 3ph motor using a VFD; however, on receipt I noted that the motor is single voltage (400/415v) and not as straight forward to swap over to delta so that I can hook it up to a 220v VFD (I think)...

At this stage, I don't really know how well the machine will run once set up and I don't want to drop £500 on a rotary converter or 220 to 400v VFD without first seeing the machine run. Catch 22 situation I suppose. What makes it worse is that I have a single to three phase VFD with an output of 220 volt that I was hoping to use...

Are there any options that I am missing? Here is a photo of the motor badge, and what is inside the wiring box.

Edited By SillyOldDuffer on 21/06/2022 18:33:19

Let's just set something straight for the record: the quill is NOT EXTENDED beyond maybe 6mm at most. It might look like it, but it isn't.

Second I don't see why a small RF45 style mill could not machine cast iron. It can, no doubt about that. I've just finished milling out slots with a 6mm end mill, no vibration whatsoever and the cuts have a great finish. This particular carbide shell may not be suitable, but previous comments contain videos showing certain shell mill / cutter combos work fine.

Personally, I'm satisfied my problems were caused by poor workholdong setup coupled with the wrong cutters.

Ok, this vice is new to me and tbh I didn't even think of that. Always used a standard milling vice. Can you explain further? I presume you want the screw to extend underneath the part and as far back toward the fixed jaw as possible to ensure maximum side force? Cheers 

Edited By Jak2g on 10/04/2022 21:02:49

I think it's a couple things. Firstly, the inserts aren't ideal for cast. That probably didn't cause the main issue though. Second, and primarily, I think the work shifted in the vice. I say this because it happened today, again, whilst using an hss shell mill (50mm). I had face milled almost everything required, and then when I was coming in on the work it visibly lifted the part and stalled the machine. I think I underestimated how when the sides are not completely parallel, even if you REALLY clamp down the piece, it could have little surface area being clamped and therefore it's actually not in there very tightly after all. Second, with the workpiece extending so far out of the vice, it acts as a lever - thereby compounding the problem.

I'm used to using small milling cutters, mainly 10mm and below - this is my first foray into facing. What I'm most surprised by is how much force the cutter has on the piece. You have to be very careful to have it clamped TIGHTLY with full contact on the jaws of the vice. Also, the work has to be as low as possible. This makes working on a piece projecting high up out of the vice difficult to some extent, but I think that if the sides were parallel and contact secure on the vice this shouldn't be a problem.

Hrmm.. Im wondering whether I would be better off with different inserts. This is what the general description is for the SEKT 1204 insert:

Carbide Inserts for Milling PVD Coated Grade NK135 (P35–M35–S15 + PVD TiN (Ti–Al–Si)N Coating) Main application – Carbon & Alloy Steel, extended application – Stainless Steel & Hi–Temp alloy

Whereas, the SEHT 1204 Is this:

SEHT 1204 AESN Carbide Inserts for Milling in Grade UM25 (P25 M25 K30 S15 + NaCo3 PVD Coating) Main application, Steel & Stainless Steel, extended application Cast Iron and High temperature Super Alloys (HRSA)

Jason - I can most certainly tell you that I am feeding slower than any of those videos, probably half as fast. Unfortunately I do not have power feed, so my knowledge of feed speed is relatively low. Regardless though, it shouldn't have bitten in to the material should it, I mean, theoretically I could run feed as slow as I like, get a crap finish, but still it shouldn't dig in. Wondering therefore if it is simply not mounted ridgidly enough, it's a heavy piece, but tightened down well.

Hi all

Firstly, thank you all for the input. I would have responded sooner but did not even realise there had been replies (no emails received for some reason). Anyways..

The reason I'm use one parallel and a rod is to avoid a camming action. Perhaps naievely I'm trying to square the block as precisely as possible, and this is what I've seen done (oxtools on YouTube demonstrates this, as do others). Perhaps I should leave the 'precision' squaring for after I've got it reasonably square by using the whole of the vice. So, that's why one parallel - I do have two to hand, lol.

Regarding the quill, Jasonb is bang on. The quill is extended only enough to allow engagement of the fine feed mechanism. In other words, very little.

I DEFINITELY think depth of cut and feed have something to do with it. The inserts are from APT. They are coated SEKT inserts for steel. The min cut on the box says 2mm, but that ain't going to happen on this machine. I believe the geometry is right, as it is nice and positive. Some people have commented before on how the ground inserts for aluminium work well on smaller machines, perhaps this would be something to try? I have used the face mill on steel, and I was getting very good chips flying everywhere - but with the cast, it's more like dust.

I switched over to a 50mm hss cutter, and noted that the tool was much sharper feeling than the inserts. The HSS cutter at that depth, and deeper felt like it was slicing through nicely, and good chips were produced. This has made me re-tnink carbide tooling, but I would like to find out where I am going wrong. Can the conclusion be that the cutter and gemoetry is good for steel, but not cast iron at the DOC this machine is capable of? Or perhaps I'm being too reserved and should try a deeper cut?

NB - this is continuously cast gr 17 cast iron, like what JasonB is holding.

Edited By Jak2g on 07/04/2022 18:42:24

Good evening all

Thinking my machine was up to the task, I bought a 50mm 5 insert SEKT face mill to use on some cast iron.

I was running at approximately .002" DOC, About 3/4 of the tool cutting, conventional milling, manual feed.

Part way through the cut, I started to get vibration and it just felt.. sketchy. I turned the machine off, and it appeared the cutter started to dig in to the material.

All unused ways were locked. The material was tight in the vice.

What I'm wondering is: (a) is this tool suitable for my machine (b) perhaps I should have roughed the surface out using an end mill and then finished with the face mill (although I'm skeptical this would help, the DOC was very small to begin with).

It's hard to describe, but running the cutter just felt sketchy. It felt like it was on a knife edge - like the slightest bit of interference would cause a problem and chatter and potentially cause the cutter to grab.

Other things to mention: I've checked spindle runout, all is good. Obviously the mill was screwed on tight, drawbar tightened appropriately, etc.

Ay suggestions to point me in the right direction would be appreciated.

Thanks

P.s. I've added some photos, one of which you can see where the tool started to dig in, and another where you can see how this big piece of cast iron is in the vice etc. 

Edited By Jak2g on 06/04/2022 22:15:38

Edited By JasonB on 07/04/2022 06:58:23

Good afternoon all

I'm still working on this and have recently broken down the entire saddle / cross /btop slide assembly and cleaned everything thoroughly including the screws.

Whilst doing this I was considering the cross-slide Gibs and reading a copy of Connelly's scraping and rebuilding machine tools book (which is very useful!). It seems that the cross slide Gibs are 'angular' Gibs, but I've become slightly confused when considering how they were fitted and adjusted. There are cap head screws that go through the cross slide table and into the Gibs - but also gib adjustment screws on the side of the cross slide table. When I disassembled the cross slide, the cap head screws were very tight, which I imagine would have the effect of sucking the gib strips up to the bottom side of the cross slide table. With that being the case, how do the gib adjustment screws on the side of the table have any effect? Are the cap screws 'locking' screws, in that you adjust the gib strips using the screws on the side, and then lock the gib strip in place by tightening the cap head screws?

Cheers!

Hi all -

I do plan to dowel the topslide and cross slide Gibs, but the saddle Gib - from what I can tell - is dowelled already. The third gib screw inserts into a hole on the gib strip, thereby locating the gib strip and also, one would think, reduce movement when adjusting the others. This is lacking on the top and cross slide, which is why I plan to dowel them as per GT's book (which I must say is probably the best book i own, highly recommended!!).

Martin: I could be misunderstanding you, but the issue is as soon as I tighten the saddle gib the saddle fouls as it moves toward the TS end of the bed. I don't have any noticeable vertical (z) play in the saddle.. are you suggesting that the saddle retainer strips are tightened at the TS end so that these assist to restrict y movement / slack at the saddle with the saddle gib loosened off? I could be way off, apologies if that is the case.

Edit: went out and checked - it's not threaded, but the gib screw inserts into it and acts as a locator. Just looked up some photos of late model super 7 saddle Gibs, and this seems standard. Got excited there for a second and thought the gib strip might have been incorrect.. 

Dave: my measurements could be off here or there, but not by much. I'm, let's say 80% confident that my measurements of the front shear width are accurate, at least for the purposes of comparing measurements along the shear. BUT..

you've got me wondering about the gib strip. It looked brand spanking new to me upon removal. The gib strip is rectangular, and only has one hole about two thirds of the way to the 'right' side (TS end) of the gib strip. That hole is threaded, and the third adjustment screw threads into it. It does not have any dimples or anything for the other adjustment screws. I've never seen a myford saddle gib strip before, does this sound correct or has someone just jammed some gauge plate in there to be used - the threaded hole seems odd, because surely the third gib screw would go through and actually meet the bed (I'd need to check this, possible that the end of the thread has been fouled so that doesn't occur.. but still).

Edited By Jak2g on 19/12/2021 17:17:05

Hello everyone

Firstly, thank you all for your input.

I got my hands on a 25-50mm micrometer and taken some careful measurements along the bed at 30mm intervals, as suggested by Martin. Here's what I found:

The width of the front shear at the very start of the bed (toward the HS) is 44.43mm. This is exactly the same as at the very end of the bed (at the TS). This makes sense because both extremes are not used often.

The width begins to narrow at 60mm from the headstock to 44.42mm, and at 90mm from the headstock it is at 44.41mm. It remains as 44.41mm until 330mm from the headstock, where widens back to 44.42mm. It remains 44.42mm wide until 540mm from the headstock, where it becomes (and remains from there forth) to be 44.43mm.

From the above, it is clear that there is a .02mm difference between the most used portion of the bed, and the tailstock. That's just under a thou in old money.

I'm fairly surprised that this level of wear would cause the issues I was experiencing, but I imagine that any issues are compounded by wear to the inner guide on the bottom of the saddle.

With the apron removed and the saddle free to slide up and down along the bed, I carefully tightened the gibs (middle screws first, followed by the one nearest the HS, and then the last one toward the TS). My measurements are 'verified' in action, because the saddle moves freely nearish to the headstock, but then tightens at around 540mm from the headstock. It also tightens if you move the saddle forward to as close as you can get to the HS, right at the very beginning.

To see whether the wide guide mod would help, I took a .4mm shim of phosphor bronze and put it between the saddle and the rear face of the rear shear. The effect of this is that when the gib is tightened, the saddle inner guide rail does not contact the rear fact of the front shear. This worked, and the bed slid freely from one end of the bed to the other.

What I've learnt from this is that the difference between 'tight' and 'loose' when dealing with gibs and ways, etc, is VERY small. it seems that a mere thou' of wear can cause problems (when compounded with slight wear on the saddle inner guide).

Now, to remedy the issue I will be doing the wide-guide mod, but am just deciding the best material to use to line the saddle (on the rear inside face). Do you guys think gauge plate would be suitable? That seems the way some have went, but most suggest that rulon or turcite B would be better (if they had it to hand). I can't find any of this stuff easily in the UK - does anyone know where I could get a small amount (enough to fix to the saddle)?

Have to admit you had me concerned for a second!

Prhaps a silly question, but would a saddle from a later model post 1972 work on an earlier pre 72 super 7?

Cheers for all the information, I think I'll look into the wide guide conversion.

What about the saddle suggests it's not a super7? Says super7 on the machine and serial number of the bed matches?

Here's a photo of the saddle, if that helps.

I've got a super7 of late 1960s vintage, so it adopts the narrow guide saddle.

The saddle operates smoothly and there is no play when toward the headstock end and in the middle of the ways, but when I move it further than half way toward the tailstock it gets stiff, very stiff to the point that you don't want to crank it when it nears the tailstock.

Its a new machine to me, so I did some research and anticipated that the inner edge of the front way would be worn toward the HS, and that the tightness could be compounded by the narrow guide having been worn, mostly toward the tailstock.

Today, I stripped it down and to the naked eye the narrow guide looked near perfect. Unfortunately I do not have an appropriate micrometer to measure between the front edge of the saddle and the narrow guide, but I used a mitutoyo digital caliper on the gap at both ends and the middle (the readings will not be perfect, but they are averaged and I think fairly indicative of the gap). Toward the headstock I have 50.44mm and toward the tailstock 50.21mm. at the middle I have 50.3mm. according to these readings, the inner guide is actually less warn toward the tailstock, which surprised me but also reassured me that my eyes were working pretty well.

I then looked at the gap between the ways. Scraping marks from factory are present on inner edge of the rear way all along. Scraping marks are present on the inner edge of the front way from the tailstock to midway along toward the headstock, and then fade. I tried to get some representative readings from my digital caliper but it was no use. In any event, there was definitely some ware on the inner edge of the front way, but not a 'lot' - visually they look in good condition as well.

Latly, I used the tailstock to provide an indication of ware toward the headstock by adjusting the Gibs with the TS at its proper end - no play evident - and slid it all the way to the headstock -at that point, there was some play evident but a ' fairly' small amount, nothing drastic.

Ayways, my primary goal is to get this thing operating smooth allt he way to the tailstock end, and I was considering to alter the saddle to operate off the wide guide, i.e. the inside face of the rear way - but seeing that the saddle is not very worn, and the ways are also seemingly not 'that' worn, I wanted to make sure I wasn't overlooking anything first.

I'm relatively new to model engineering, so whilst I have a head scrrwed on (I think?!) I am not a machinist by trade, so apologies before hand if what I've said above doesn't make sense.

If anyone could point me in the right direct / share their thoughts on this situation and what I want to achieve in the end, I'd be very appreciative.

Cheers

Edit: 

Two other things. Even with the saddle gib loosened off completely, there is a noticeable difference in effort required to wind the saddle toward the tailstock (from about 2/3 of the way along), and the gib strip looks brand new to me - it is approximately 4.58mm wide the entire length.

Edited By Jak2g on 16/12/2021 20:16:30

Thanks everyone. I can't drill any holes in the disc unfortunately or I'd definitely be putting it on the faceplate.

I don't have any tools for boring on the mill, but this is something I could get. I was thinking the lathe could have been quicker, given that the largest drill I have is well under 19mm, so I think I'll be boring it out for a while!

I do want to have good concentricity because I'll be using this as a lapping disc mounted to a 3 phase motor and vfd 

Edited By Jak2g on 30/04/2021 10:29:14