Member postings for AJAX

Correction: I should have said 57.5 metres per minute (not second!) but I think you realised that.

An updated video which may answer some of the issues / questions that have been raised in this thread. Thanks to everyone who has taken the time to read my posts and offer their advice - it is hugely appreciated.

Thanks for posting the photos - it's nice to see other examples of this (and similar) mills to see what others have done. The motor pulley was in poor condition on my machine but that was easily replaced and the others are all in good condition. I think the jury's out on whether it would be worth my while changing to poly-v belts and I should try different cutters / lower spindle speed first.

Out of curiousity, did you have a quick return lever on your machine? Mine was missing the lever and I machined a replacement but haven't really found it necessary. I see you have a t-nut / stop mounted to the front of the table - was this for a power feed add on or simply to limit travel?

The arbour is 3 MT which is handy as it matches my lathe and ER collet set if I decide to use end mills.

I much appreciate your observation about supporting the arbour and how larger horizontal milling machines are used. I never planned to buy a horizontal mill but this one was too good to pass by and I enjoy a new (old) toy to play with. If I ever find time I may try converting it to a vertical mill.

"would any one try using a parting tool a half inch wide !!" -- good point!

Anyone interested in buying a job lot of large milling cutters?

If the current setup allowed a small increase in belt tension I would do so, but as you are now aware there is no means to do so other than changing the belt. Rightly or wrongly, I feel the belt tension is about right apart from the problem of belt vibration/oscillation at higher speed which I'm starting to believe is due to other problems (e.g. feed rate or unsuitability of the cutter).

I doubt changing to a 3 phase motor will fix this problem but I'm happy to convert as I already have a spare VFD. It might also give me some flexibility over spindle speed that I lack through the very limited pulley options.

Regarding the current setup, the pulleys have been chosen to give the slowest spindle speed and best belt alignment.

The vibration only happens when taking a cut using the full width of a 5 or 6" x 1/2" cutter. I have *many* cutters that were included with this mill but most of them are clearly too big for this machine, including slab mills, etc. However, I have enough smaller cutters to know that I can take decent cuts with no vibration. I should point out the 5 and 6" cutters work well (with no vibration) when I can progress the machining on the y axis taking no more than about 2mm at a time.

I will probably be getting rid of the unneeded tooling in due course. A couple of items have already been sold, so the machine has only cost me £60 plus the motor mount purchased new.

The speed chart is something of a red herring as the motor and motor pulley are not original. 120RPM is about the slowest with the current setup and I now understand that may be somewhat high for a larger cutter on this size machine.

Thanks for all your help,

Brian

The intermediate jackshaft is a fixed stub welded to the milling machine base. It appears to be original and offers no form of adjustment for belt tension. The belts are currently set up for best alignment giving a driven speed of approximately 120 RPM. With a 6" cutter that equates to a cutting speed of 57.5 ms-1 which does not seem excessive.

I agree that the coarseness of the cutter is contributing to the vibration, but should point out that when several teeth are engaged with the cut the machine handles the task very well.

New poly-v pulleys would cost me significantly more than the machine and that's something I'm trying to avoid. Spending money.

I have just created an album for those not familiar with this machine.

That's my video just after adding the motor mount which I have to say has worked very well. However, it doesn't address the problem of upper belt vibration when using larger cutters.

Incidentally, I could post more videos if anyone is interested.

Thanks for your thoughts - everything is welcome.

There is no significant vibration in the motor drive belt. Incidentally, the motor drive belt is easy to adjust as the motor is on a sliding mount.

The second belt (driving the spindle) runs between two fixed pulleys with no adjustment and that is an additional reason for adding an idler pulley. This belt is long and relatively low speed, whereas the oscillations are relatively high frequency and relate to the cutter being used (6" 18 tooth) and not a "hump" or two in the belt. However, I did try changing the belts with no improvement. I also considered changing to a link belt (as used on my Denford lathe) but doubt it would offer any improvement unless able to absorb the "shock" of the cutting action.

Currently a 3/4 HP single phase motor but I do have a spare VFD and had originally planned to install a larger 3 phase motor. It's easy to swap the motor as it is now mounted on an adjustable mounting rail. However, the 3/4 HP appears perfectly adequate so far.

The belt moves approximately 10mm under a force of 10N.

The two pulleys measure 70mm / 200mm with a distance between centres of around 430mm.

Hi, this is my first post!

I recently purchased an old Ajax AJ8 horizontal milling machine in remarkably good condition for not a lot of money. I have since fitted a replacement motor and used the machine with good effect but there is a niggle with belt vibration. There is no vertical head, so everything is done on the horizontal spindle.

The machine has two v-belts, one from the motor to a 2-step pulley and the second belt to the main cutter spindle. Both belts are in my opinion correctly tensioned. All bearings are good, lubricated and tooling sharp.

When using a moderate size cutter (e.g. 5" x 1/2" I have noticed some vibration developing in the "slack" side of the final drive belt and this significantly adds to workshop noise. The whole machine is sufficiently heavy that the cut quality appears unaffected. I am mostly milling mild steel, with some cast iron.

I have considered adding an idler pulley to the problem belt, thus shortening the distance between centres as I think this should eliminate the problem. However, before I attempt this fix I would welcome any other suggestions.

On a different but related matter, I need to make a chip tray for the machine and if anyone has the same miller I'd be interested to know what setup you use. I'd like to include a coolant pump and sump.

Brian